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Pricing and indices methodology as from 3rd December 2015

The information in this document is current as at the Publication Date. Polishedprices does not accept responsibility for damages, either direct or indirect caused by an error or omission in this document.

Contents

General Description

Submitters

Pricing Grid

Filter for Anomalies

Factoring

Calculation of the Normalised Price

Diamond Price Indices Methodology

General Description

The document describes the process by which the polished diamond prices submitted to polishedprices.com (PP) are screened for anomalies, factored, have various algorithms applied depending upon their position on the price grid. This process takes place before the prices are made available for inclusion in one of the Diamond Price Indices published on the http://www.polishedprices.com/ website (PP Website) or made available to data subscribers.

Submitters

The diamond transaction prices are submitted each day by the Submitters listed on the PP Website.  In order to submit prices to PP the submitters must have signed the Submitter Agreement and Submitter Code of Conduct.

Each submitter agrees with PP in advance which prices in the grid they will submitting.  All prices have to be submitted by 8.00 a.m. London time in order to be included in the calculation for the day and the day’s calculation includes all prices since the previous 8.00 a.m. deadline on the previous business day. This means that all submissions received over the weekend are included in Monday’s calculation.

Pricing Grid

The complete pricing grid for colour and quality can be seen below.

 

D

E

F

G

H

I

J

K

L

M

IF

x

x

x

x

x

x

x

x

x

x

VVS1

x

x

x

x

x

x

x

x

x

x

VVS2

x

x

x

x

x

x

x

x

x

x

VS1

x

x

x

x

x

x

x

x

x

x

VS2

x

x

x

x

x

x

x

x

x

x

SI1

x

x

x

x

x

x

x

x

x

x

SI2

x

x

x

x

x

x

x

x

x

x

SI3

x

x

x

x

x

x

x

x

x

x

I1

x

x

x

x

x

x

x

x

x

x

I2

x

x

x

x

x

x

x

x

x

x

I3

x

x

x

x

x

x

x

x

x

x

The sizes of diamonds that are submitted for the grid are listed below.

Carats

3

2

1.5

1

0.9

0.7

0.50

0.4

0.3

 

3ct

2ct

6gr

4gr

90pts

70pts

50pts

40ptd

30pts

Each size of stone ranges from its size in the table above to 2 decimal places above its weight before changing to the size above, therefore a 0.5 carat stone can range in size from 0.5 carats to 0.69 carats.

Filter for Anomalies

The first filter applied to the submitted prices is to check whether the submitted prices for each price point is within a tolerance from the previous day’s price for each price point as agreed at the quarterly Oversight Committee meeting.  Currently the tolerance is set at 20% across all price points.  However PP has the ability to set different tolerances for each single price point or blocks of points as is agreed with the OC. So, currently, the submitted price can be up to 120% of the previous price or down to 80% of the previous price.  If they are within the tolerance they are included in the calculation for the day, if not they are rejected from the calculation.   

Any changes to the tolerance levels will be published following the OC meeting at which the changes are sanctioned.

Factoring

The prices then have the following factors applied to them dependent on their certificates and make.

Shape

All polishedprices.com indices are based on round shaped diamonds.  The factors for shape are used to create a pricing matrix for fancy shaped (or non round diamonds).

Fine Polished Single Price Point

Mixed Polished Parcel

Commercial Polished Parcel

Shape

Factor

Factor

Factor

Baguette

0.60

0.60

 

Emerald

0.80

0.80

0.80

Heart

0.75

0.75

 

Marquise

0.78

0.78

0.78

Oval

0.80

0.80

0.80

Pear

0.80

0.80

0.80

Princess

0.80

0.80

0.80

Radiant

0.75

0.75

 

Round

1.00

1.00

1.00

Trilliant

0.70

0.70

 
 

D

E

F

G

H

I

J

K

L

M

IF

Fine Fine Fine Fine Fine Fine Comm Comm Mixed Mixed

VVS1

Fine Fine Fine Fine Fine Fine Comm Comm Mixed Mixed

VVS2

Fine Fine Fine Fine Fine Fine Comm Comm Mixed Mixed

VS1

Fine Fine Fine Fine Fine Fine Comm Comm Mixed Mixed

VS2

Fine Fine Fine Fine Fine Fine Comm Comm Mixed Mixed

SI1

Comm Comm Comm Comm Comm Comm Comm Comm Mixed Mixed

SI2

Comm Comm Comm Comm Comm Comm Comm Comm Mixed Mixed

SI3

Comm Comm Comm Comm Comm Comm Comm Comm Mixed Mixed

I1

Mixed Mixed Mixed Mixed Mixed Mixed Mixed Mixed Mixed Mixed

I2

Mixed Mixed Mixed Mixed Mixed Mixed Mixed Mixed Mixed Mixed

I3

Mixed Mixed Mixed Mixed Mixed Mixed Mixed Mixed Mixed Mixed

The Fine Prices are noted by the section of the price grid coloured red, the Commercial Prices in the sections coloured blue and the Mixed Prices in the sections coloured green.

Certificates and Make

Certificate Calculation Factors

Make Calculation Factors

Certificate

Factor

Make

Factor

Forever Mark

0.9500

EX - EX

1.000

GIA

1.0000

Ex-Ex-Ex

1.050

IGI

0.9000

G-VG

0.850

EGL

0.8500

VG -G

0.900

HRD

0.9500

VG-VG

0.950

None

0.8500

   
   

G - G

0.800

   

Lower Makes

0.700

Calculation of the Normalised Price

The normalised price is automatically calculated daily using the following methodology.

The index is divided into two spheres or sections for calculating the normalised price.  The reason for this is to mimic how the industry actually handles certain types of stones.  Usually when a stone is being cut and polished the manufacturer targets the best compromise between size and quality, where the higher the quality the importance of size is relatively diminished.  In lower colours and qualities that is GIA grade L  colour and below, and quality SI1 and below, the most important criteria for the manufacturer is achieving the maximum yield or the largest possible polished stone as possible, quality and the loss of weight to achieve a better quality stone is very much a subsidiary goal.  The consequence is that in lower colours as defined there are rarely the top qualities manufactured.  It is rare to find a flawless M coloured stone for instance.

Therefore for the purposes of calculating the normalised price for these lower colours the methodology uses blocks of price points to avoid distortions to the prices.

All the prices that appear on the PP Website are normalised and therefore all published indices, which are for round stones, are using them.

Normalised price calculation for all colours and qualities above K & SI1 and therefore the price points below:

 

D

E

F

G

H

I

J

IF

x

x

x

x

x

x

x

VVS1

x

x

x

x

x

x

x

VVS2

x

x

x

x

x

x

x

VS1

x

x

x

x

x

x

x

VS2

x

x

x

x

x

x

x

Each price point is expressed as a percentage or discount / premium to the PP Benchmark Price list (BPL).  The PP Benchmark Price list is created by taking the average price reported to PP over the previous calendar year having applied the factors described earlier.

The new Normalised Price Percentage Difference (NPPD) is a discount or premium to the BPL is then calculated by changing the previous day’s NPPD by the following ratios from the surrounding price points.

For those price points in the grid which are surrounded by other categories or price points, the price change consists of half (50%) for that specific point plus 6.25% for all those 8 surrounding price points (8x 6.25% = 50%), therefore recognising the correlation between price points but weighting heavily in favour of the actual price point.

6.25%

6.25%

6.25%

6.25%

50.0%

6.25%

6.25%

6.25%

6.25%

Using the same principle for price points on the side of the grid, the weighting for the surrounding points is half (50%) for the point, plus 10% of each of the 5 surrounding points,

10.0%

10.0%

50.0%

10.0%

10.0%

10.0%

For the 4 corner points it is 50% for the point, plus 16.66% of the 3 surrounding points.

50.0%

16.66%

16.66%

16.66%

Examples

Consider a corner point where the following changes had been recorded.

-5.0%

10.0%

7.0%

-1.0%

The following days point would be:

(-5%*50%)+(10%*16.66%)+(7%*16.66%)+(-1%*16.66%) = 0.2%.

Had there been no data for that day for the point in question

 

10.0%

7.0%

-1.0%

The calculation for the next day would be:

(10%*16.66%)+(7%*16.66%)+(-1%*16.66%) = +2.7%.

For a side point with the following changes:

-5.0%

10.0%

7.0%

-1.0%

-2.0%

5.0%

The calculation would be:

(-5%*10%)+(10%*10%)+(7.0%*50%)+(-1.0%*10%)+(-2.0%*10%)+(5%*10%) = 4.2%

And for a central point with price changes:-

-5.0%

10.0%

3.0%

7.0%

-1.0%

-6.0%

-2.0%

5.0%

0.0%

The calculation would be:

(-5%*6.25%)+(10%*6.25%)+(3%*6.25%)+(7%*6.25%)+(-1%*50.00%)+(-6%*6.25%)+(-2%*6.25%)+(5% *6.25%)+(0*6.25%) = 4.2%

The Normalised price calculation for all colours and qualities equal or below K- SI1

Table of various blocks for categories equal or below K-SI1

 

D

E

F

G

H

I

J

K

L

M

IF

              x x x

VVS1

              x x x

VVS2

              x x x

VS1

              x x x

VS2

              x x x

SI1

              x x x

SI2

x x x x x x x x x x

SI3

x x x x x x x x x x

I1

x x x x x x x x x x

I2

x x x x x x x x x x

I3

x

x

x

x

x

x

x

x

x

x

The Upper quadrant D IF to J VS2 contains approximately 50% by value and 25% by weight of all polished stones

For colours and qualities equal or below K and SI1, although there will be prices quoted for each individual colour/quality the prices will move in blocks because of the high correlation in prices between the points and because of the lower number of submissions for these price points.

The 8 blocks are:

Block

No of Price Points

Colour

Colour Letters

Quality

Estimated % Value

1

9

Red

K-M

IF-VVS2

1.6%

2

6

Dark Blue

K-M

VS1-VS2

2.2%

3

9

Yellow

D-F

SI2-SI3

4.7%

4

12

Light Green

G-J

SI2-SI3

21.1%

5

9

Medium Blue

K-M

SI2-SI3

5.5%

6

6

Purple

D-F

I1-I2

2.3%

7

8

Light Blue

G-J

I1-I2

9 .4%

8

6

Dark Green

K-M

I1-I2

3.0%

Percentage movements within the blocks will be amalgamated and the percentage movement is then applied to all the previous day’s NPPDs within the block.  For instance if a submission is received for a single price point in the block, then the percentage movement is calculated for that price point and the same percentage applied across all the price points in the block. If there are two submissions received for different price points in the block, then the two price movements are averaged and the average percentage movement are applied across the block; and so on for more price submissions received.

The Normalised price calculation for all colours within row I3:

If no submissions are received on a given day for any stones in row I3:

The quoted price for I3 quality will move by the same percentage as the (I1-I2) range for the corresponding colour according to its block. For example:

I3 Quality Number of Blocks Per Table in the table above

D-F

6 (purple)

G-J

8(light blue)

K-M

6 (dark green)

If a submission is received for a price point on the I3 row:

The submitted price is used for the price point, however there is a further validation carried out to ensure consistent prices along the row.  If the price causes an anomaly in the prices along the row (i.e. where a price for a particular colour received is lower than the price of the colour below it or higher than the price for the colour above it) then the prices per price point are sorted in descending order through the colours which in effect moves the submitted price to the most appropriate colour to fit in with the descending order of prices.

Note in some cases this could result in the price being moved more than one colour up or down from the submitted colour.

Daily Price Verification of the Normalised Prices

The same daily data is run on two separate computers, in two different locations, using different computing programmes to verify the prices before they are published each day and used for the creation of the indices.

There is a match carried out between the calculations and mathematically there is inevitably a possibility of rounding errors between the two systems given the sequence of calculations that have to take place to create the normalised prices as described above.

Therefore the policy of PP is to ignore any rounding errors up to a value of $1, remembering that in fact all prices are published to the nearest $10 per price point.  Where the prices are within the $1 tolerance it is the Calculation Agent’s version of the price that is used.

The agreed prices for any day are taken as the starting point for the calculation of the normalised prices for subsequent day.

In the event of any difference being greater than $1, it is logged and will be investigated.  If, there is no resolution as to the cause of the difference at the time of publishing the index at 12.00 noon London time and the difference is no greater than 10% for the individual price point and that any accumulated differences have less than a 0.1% difference on the index, the previous day’s normalised price will be used.  Once the difference is resolved the submissions that have been received that made up the price are carried over and combined with the next day’s submissions to go into the calculation for the next day’s price.

A notice will be put on the PP website to explain where this process has occurred so that it is fully transparent that the price of the following day includes two day’s worth of submissions. All differences over the $1 tolerance are logged and will be scrutinised by the OC at its quarterly meeting to understand why they happened and how a repetition can be avoided.

Diamond Price Indices Methodology

Index Equations

The index at time t = (∑i,j,k (Wi,j,k × Pi,j,k(t)) / ∑i,j,k (Wi,j,k)) / (∑i,j,k (Wi,j,k × Pi,j,k(0)) / ∑i,j,k (Wi,j,k)) * 100

where

Wi,j,k is the weight for size i, colour j, quality k

Pi,j,k(t) is the price at time t for size i, colour j, quality k

t=0 is the date where the index is set at 100, currently January 2004

Weighting used for index calculations

For all indices published by polishedprices the same weightings, which are designed to reflect the overall amount of new polished being produced , are used.

The weightings applied for each size of diamonds are:

3ct

6.455%

2ct

8.029%

6gr

10.587%

4gr

13.946%

90 pts

6.499%

70 pts

8.597%

50pts

13.225%

40 pts

8.165%

30 pts

24.496%

Total

100.000%

The weighting for each colour/quality within size are:

3ct

                   
 

D

E

F

G

H

I

J

K

L

M

IF

0.019%

0.167%

0.266%

0.468%

0.590%

1.094%

1.032%

0.696%

0.439%

0.260%

VVS1

0.021%

0.186%

0.296%

0.521%

0.657%

1.217%

1.148%

0.774%

0.488%

0.289%

VVS2

0.027%

0.241%

0.384%

0.676%

0.852%

1.579%

1.490%

1.005%

0.633%

0.376%

VS1

0.023%

0.203%

0.323%

0.569%

0.717%

1.328%

1.253%

0.845%

0.532%

0.316%

VS2

0.033%

0.288%

0.460%

0.810%

1.020%

1.891%

1.784%

1.203%

0.758%

0.450%

SI1

0.037%

0.331%

0.529%

0.930%

1.172%

2.172%

2.050%

1.382%

0.871%

0.517%

SI2

0.050%

0.444%

0.708%

1.246%

1.570%

2.909%

2.745%

1.851%

1.166%

0.692%

SI3

0.064%

0.570%

0.910%

1.599%

2.016%

3.736%

3.525%

2.377%

1.498%

0.888%

I1

0.046%

0.408%

0.650%

1.144%

1.441%

2.671%

2.520%

1.699%

1.071%

0.635%

I2

0.046%

0.403%

0.643%

1.131%

1.425%

2.641%

2.492%

1.680%

1.059%

0.628%

I3

0.009%

0.077%

0.122%

0.215%

0.271%

0.503%

0.475%

0.320%

0.202%

0.120%

2ct

                   
 

D

E

F

G

H

I

J

K

L

M

IF

0.037%

0.230%

0.328%

0.541%

0.694%

1.075%

0.889%

0.622%

0.343%

0.223%

VVS1

0.040%

0.251%

0.358%

0.591%

0.758%

1.174%

0.971%

0.679%

0.374%

0.244%

VVS2

0.062%

0.388%

0.553%

0.914%

1.171%

1.814%

1.500%

1.049%

0.578%

0.376%

VS1

0.046%

0.289%

0.412%

0.680%

0.872%

1.350%

1.117%

0.781%

0.430%

0.280%

VS2

0.069%

0.432%

0.616%

1.018%

1.305%

2.021%

1.672%

1.169%

0.644%

0.419%

SI1

0.071%

0.447%

0.638%

1.054%

1.350%

2.092%

1.730%

1.210%

0.667%

0.434%

SI2

0.091%

0.571%

0.815%

1.346%

1.725%

2.673%

2.211%

1.546%

0.852%

0.554%

SI3

0.118%

0.741%

1.058%

1.747%

2.239%

3.469%

2.869%

2.006%

1.105%

0.719%

I1

0.097%

0.610%

0.870%

1.437%

1.842%

2.854%

2.360%

1.650%

0.909%

0.592%

I2

0.081%

0.512%

0.730%

1.206%

1.545%

2.394%

1.980%

1.385%

0.763%

0.497%

I3

0.023%

0.143%

0.204%

0.336%

0.431%

0.667%

0.552%

0.386%

0.213%

0.138%

6gr

                   
 

D

E

F

G

H

I

J

K

L

M

IF

0.035%

0.221%

0.333%

0.599%

0.686%

1.141%

0.943%

0.543%

0.340%

0.208%

VVS1

0.039%

0.248%

0.373%

0.671%

0.768%

1.277%

1.055%

0.608%

0.381%

0.233%

VVS2

0.060%

0.379%

0.571%

1.027%

1.175%

1.955%

1.615%

0.930%

0.583%

0.357%

VS1

0.056%

0.358%

0.539%

0.970%

1.110%

1.846%

1.525%

0.878%

0.551%

0.337%

VS2

0.068%

0.432%

0.651%

1.170%

1.340%

2.228%

1.841%

1.060%

0.665%

0.407%

SI1

0.100%

0.637%

0.960%

1.726%

1.976%

3.286%

2.715%

1.564%

0.980%

0.600%

SI2

0.088%

0.561%

0.845%

1.520%

1.740%

2.893%

2.390%

1.377%

0.863%

0.528%

SI3

0.103%

0.655%

0.987%

1.775%

2.031%

3.378%

2.791%

1.608%

1.008%

0.617%

I1

0.073%

0.465%

0.701%

1.261%

1.444%

2.401%

1.984%

1.143%

0.716%

0.439%

I2

0.050%

0.319%

0.481%

0.865%

0.990%

1.646%

1.360%

0.783%

0.491%

0.301%

I3

0.017%

0.105%

0.158%

0.285%

0.326%

0.543%

0.448%

0.258%

0.162%

0.099%

4gr

                   
 

D

E

F

G

H

I

J

K

L

M

IF

0.036%

0.205%

0.334%

0.647%

0.825%

1.142%

0.794%

0.510%

0.312%

0.236%

VVS1

0.040%

0.229%

0.373%

0.722%

0.921%

1.275%

0.886%

0.569%

0.348%

0.264%

VVS2

0.047%

0.269%

0.439%

0.849%

1.083%

1.499%

1.042%

0.669%

0.410%

0.310%

VS1

0.044%

0.251%

0.409%

0.791%

1.009%

1.396%

0.970%

0.624%

0.382%

0.289%

VS2

0.068%

0.389%

0.634%

1.226%

1.564%

2.165%

1.505%

0.967%

0.592%

0.448%

SI1

0.072%

0.413%

0.673%

1.303%

1.663%

2.301%

1.599%

1.028%

0.629%

0.476%

SI2

0.088%

0.506%

0.825%

1.597%

2.037%

2.820%

1.960%

1.260%

0.771%

0.583%

SI3

0.107%

0.611%

0.995%

1.926%

2.457%

3.401%

2.363%

1.519%

0.929%

0.704%

I1

0.074%

0.424%

0.691%

1.338%

1.707%

2.363%

1.642%

1.055%

0.646%

0.489%

I2

0.076%

0.436%

0.711%

1.375%

1.754%

2.428%

1.687%

1.085%

0.664%

0.502%

I3

0.058%

0.335%

0.545%

1.056%

1.347%

1.864%

1.296%

0.833%

0.509%

0.386%

90pts

                   
 

D

E

F

G

H

I

J

K

L

M

IF

0.004%

0.028%

0.049%

0.086%

0.101%

0.150%

0.115%

0.059%

0.031%

0.031%

VVS1

0.013%

0.084%

0.148%

0.259%

0.302%

0.449%

0.344%

0.176%

0.094%

0.092%

VVS2

0.044%

0.276%

0.483%

0.847%

0.987%

1.468%

1.124%

0.574%

0.306%

0.302%

VS1

0.039%

0.244%

0.428%

0.751%

0.875%

1.302%

0.997%

0.509%

0.272%

0.268%

VS2

0.051%

0.318%

0.557%

0.976%

1.138%

1.692%

1.296%

0.662%

0.353%

0.348%

SI1

0.076%

0.473%

0.829%

1.454%

1.694%

2.519%

1.929%

0.985%

0.525%

0.519%

SI2

0.106%

0.661%

1.158%

2.031%

2.366%

3.519%

2.695%

1.376%

0.734%

0.725%

SI3

0.142%

0.891%

1.562%

2.740%

3.192%

4.747%

3.635%

1.857%

0.990%

0.978%

I1

0.104%

0.648%

1.136%

1.992%

2.321%

3.452%

2.643%

1.350%

0.720%

0.711%

I2

0.077%

0.482%

0.844%

1.481%

1.726%

2.567%

1.965%

1.004%

0.535%

0.529%

I3

0.031%

0.194%

0.339%

0.595%

0.694%

1.031%

0.790%

0.403%

0.215%

0.212%

70pts

                   
 

D

E

F

G

H

I

J

K

L

M

IF

0.041%

0.191%

0.348%

0.688%

0.913%

1.210%

0.713%

0.469%

0.276%

0.313%

VVS1

0.048%

0.221%

0.403%

0.797%

1.058%

1.402%

0.826%

0.543%

0.320%

0.363%

VVS2

0.051%

0.236%

0.430%

0.851%

1.129%

1.497%

0.882%

0.580%

0.342%

0.388%

VS1

0.049%

0.225%

0.410%

0.811%

1.075%

1.426%

0.840%

0.553%

0.325%

0.369%

VS2

0.070%

0.324%

0.591%

1.170%

1.552%

2.057%

1.212%

0.797%

0.470%

0.533%

SI1

0.081%

0.377%

0.688%

1.361%

1.806%

2.394%

1.410%

0.928%

0.547%

0.620%

SI2

0.101%

0.466%

0.850%

1.682%

2.231%

2.957%

1.742%

1.146%

0.675%

0.766%

SI3

0.108%

0.501%

0.914%

1.808%

2.399%

3.180%

1.873%

1.233%

0.726%

0.823%

I1

0.078%

0.362%

0.660%

1.304%

1.731%

2.294%

1.351%

0.889%

0.524%

0.594%

I2

0.087%

0.403%

0.735%

1.454%

1.928%

2.556%

1.506%

0.991%

0.584%

0.662%

I3

0.084%

0.389%

0.709%

1.403%

1.861%

2.468%

1.454%

0.956%

0.563%

0.639%

50pts

                   
 

D

E

F

G

H

I

J

K

L

M

IF

0.057%

0.267%

0.338%

0.621%

0.751%

1.020%

0.848%

0.638%

0.426%

0.540%

VVS1

0.042%

0.195%

0.247%

0.454%

0.549%

0.745%

0.619%

0.465%

0.311%

0.394%

VVS2

0.061%

0.288%

0.364%

0.670%

0.810%

1.099%

0.914%

0.687%

0.459%

0.582%

VS1

0.062%

0.292%

0.369%

0.679%

0.821%

1.115%

0.927%

0.697%

0.466%

0.590%

VS2

0.104%

0.486%

0.615%

1.132%

1.368%

1.857%

1.544%

1.161%

0.776%

0.983%

SI1

0.113%

0.531%

0.672%

1.236%

1.495%

2.029%

1.687%

1.268%

0.848%

1.074%

SI2

0.118%

0.553%

0.700%

1.286%

1.556%

2.112%

1.755%

1.320%

0.882%

1.118%

SI3

0.150%

0.705%

0.892%

1.640%

1.983%

2.692%

2.238%

1.683%

1.125%

1.425%

I1

0.152%

0.713%

0.902%

1.659%

2.006%

2.724%

2.264%

1.702%

1.138%

1.442%

I2

0.102%

0.480%

0.607%

1.117%

1.351%

1.834%

1.524%

1.146%

0.766%

0.971%

I3

0.072%

0.340%

0.430%

0.791%

0.956%

1.298%

1.079%

0.811%

0.542%

0.687%

40pts

                   
 

D

E

F

G

H

I

J

K

L

M

IF

0.084%

0.290%

0.345%

0.653%

0.683%

0.971%

0.930%

0.612%

0.422%

0.547%

VVS1

0.108%

0.372%

0.443%

0.839%

0.877%

1.247%

1.194%

0.785%

0.542%

0.703%

VVS2

0.099%

0.341%

0.406%

0.769%

0.804%

1.144%

1.095%

0.720%

0.497%

0.644%

VS1

0.113%

0.387%

0.461%

0.874%

0.913%

1.299%

1.244%

0.818%

0.564%

0.732%

VS2

0.150%

0.515%

0.612%

1.161%

1.213%

1.726%

1.652%

1.087%

0.750%

0.972%

SI1

0.120%

0.414%

0.492%

0.933%

0.975%

1.388%

1.328%

0.873%

0.603%

0.781%

SI2

0.159%

0.546%

0.649%

1.232%

1.287%

1.831%

1.752%

1.153%

0.795%

1.031%

SI3

0.217%

0.746%

0.888%

1.683%

1.759%

2.502%

2.395%

1.575%

1.087%

1.409%

I1

0.225%

0.775%

0.922%

1.748%

1.827%

2.599%

2.488%

1.636%

1.129%

1.464%

I2

0.151%

0.520%

0.618%

1.173%

1.225%

1.743%

1.668%

1.097%

0.757%

0.982%

I3

0.095%

0.326%

0.388%

0.736%

0.770%

1.095%

1.048%

0.689%

0.475%

0.617%

30pts

                   
 

D

E

F

G

H

I

J

K

L

M

IF

0.084%

0.290%

0.345%

0.653%

0.683%

0.971%

0.930%

0.612%

0.422%

0.547%

VVS1

0.108%

0.372%

0.443%

0.839%

0.877%

1.247%

1.194%

0.785%

0.542%

0.703%

VVS2

0.099%

0.341%

0.406%

0.769%

0.804%

1.144%

1.095%

0.720%

0.497%

0.644%

VS1

0.113%

0.387%

0.461%

0.874%

0.913%

1.299%

1.244%

0.818%

0.564%

0.732%

VS2

0.150%

0.515%

0.612%

1.161%

1.213%

1.726%

1.652%

1.087%

0.750%

0.972%

SI1

0.120%

0.414%

0.492%

0.933%

0.975%

1.388%

1.328%

0.873%

0.603%

0.781%

SI2

0.159%

0.546%

0.649%

1.232%

1.287%

1.831%

1.752%

1.153%

0.795%

1.031%

SI3

0.217%

0.746%

0.888%

1.683%

1.759%

2.502%

2.395%

1.575%

1.087%

1.409%

I1

0.225%

0.775%

0.922%

1.748%

1.827%

2.599%

2.488%

1.636%

1.129%

1.464%

I2

0.151%

0.520%

0.618%

1.173%

1.225%

1.743%

1.668%

1.097%

0.757%

0.982%

I3

0.095%

0.326%

0.388%

0.736%

0.770%

1.095%

1.048%

0.689%

0.475%

0.617%

These weightings are reviewed annually by the polishedprices oversight committee.

Should it be decided by that committee that world production has changed to such an extent that the standard weightings be changed, indices using the old weightings will be produced in parallel with the new weightings for a period of time.

Currently published indices

Polishedprices regularly publishes a series of indices

  • Overall Index
  • Sub-Indices
  • 1 Carat Overall Index
  • 1 Carat Fine Index
  • 1 Carat Commercial Index
  • 1 Carat Mixed Index
  • 0.5  Carat Overall Index
  • 0.5  Carat Fine Index
  • 0.5  Carat Commercial Index
  • 0.5  Carat Mixed Index
  • 0.3  Carat Overall Index
  • 0.3  Carat Fine Index
  • 0.3  Carat Commercial Index
  • 0.3  Carat Mixed Index

1 Carat Overall Index

Weight

1 – 1.24 cts

Colour

D,E,F,G, H, I, J, K,L,M

Clarity

IF, VVS1,VVS2, VS1,VS2,SI1,SI2,SI3,I1,I2,I3

The Fine indices are noted by the section of the price grid coloured red, the commercial indices be the sections coloured blue and the Mixed indices by the sections coloured green in the weightings charts.

0.5 Carat Index

Weight

050-0.59 vts

Colour

D,E,F,G, H, I, J, K,L,M

Clarity

IF, VVS1,VVS2, VS1,VS2,SI1,SI2,SI3,I1,I2,I3

The Fine indices are noted by the section of the price grid coloured red, the commercial indices be the sections coloured blue and the Mixed indices by the sections coloured green in the weightings charts.

0.3 Carat Index

Weight

0.30-0.39 cts

Colour

D,E,F,G, H, I, J, K,L,M

Clarity

IF, VVS1,VVS2, VS1,VS2,SI1,SI2,SI3,I1,I2,I3

The Fine indices are noted by the section of the price grid coloured red, the commercial indices be the sections coloured blue and the Mixed indices by the sections coloured green in the weightings charts.

Use of other weightings

Polishedprices is prepared to publish indices using different weightings should this be required by third parties, but all indices using the polishedprices name will use the standard weightings outlined above.