Welcome to Gemstone Auctioneers

Here at Gemstone auctioneers we understand the importance of providing the very latest, up to date valuation for all our gemstones, The importance of being accurate with the valuation along with the historical values charts ensures that when we quote an average retail value the valuation is as current as is possible.    

Interactive online gem appraisal model

To provide you with the most accurate online appraisal possible, we have created a sophisticated mathematical model. Each gemstone appraisal is based on a complex statistical analysis of current online sales prices for natural coloured gems. The algorithm takes into account the specific factors influencing a gem's price, such as; weight, colour, clarity, cut and shape. We collect statistical market data by examining hundreds of lots from different gem sellers every month. Please be aware that the pricing model parameters (value factors) are generally updated monthly, so any estimated value will vary slightly over time.

How we collect data

We add new online shops to our tracking list every month so our online gemstone resources are continuously growing. We thoroughly check and categorize each online resource before we assign it a value on our dependency index. To optimise accuracy we make sure that only market-balanced offers are entered into the database. All specimens with highly irregular prices are rejected and therefore have no impact upon statistical coefficients.

Gemstone dealers are more than welcome to contact us and be included in our tracking list free of charge.

Valuation model

Generally speaking, the value of any natural gemstone may be approximated by using the following formula:

Val = (L0 + L1 * W) * W * C1 * C2 * C3 * C4


L0, L1 - linear price per carat trend for selected gemstone variety,

W - weight,

C1 - color coefficient,

C2 - clarity coefficient,

C3 - quality of cut coefficient.

C4 - shape coefficient (for some gemstone types).

The values of relevant coefficients are derived by the 'Least Square Method'. Currently our statistical database contains over 70000 records, and as a rule we upload new records to our database and recalculate the coefficients on a monthly basis.

Brief history of Gemval


A group of gemologists and mathematicians started work on a web-based application for the appraisal of gemstones. Initially, we planned to develop a web tool to specifically evaluate natural sapphires. However after testing dozens of models, we discovered that the same statistical approach we'd developed for sapphire valuation could be applied to almost any variety of gemstone. Thus, after a year of compiling data and testing, Gemval.com was conceived.


Gemval.com is launched, and 480 new users registered during its first week online!


Open Alias Corporation acquires Gemval.


Gemval offers a paid-subscription service for precious gemstones, however appraisals for most of the natural gemstone varieties remain free of charge. Gemval becomes renowned in the jewelry community.


Gemval is the first to market. We begin to publish historical-value charts, and the Gemval Aggregate index (GVA).


Gemval appointed as an approved data supplier for the provision of valuation data and pricing indices for the Market News Service, The International Trade Centre UNCTAD/WTO, Geneva.


Gemval extends its statistical database, with specific color pattern parameters added for the rare gemstone varieties.


Gemval develops the color grading system and valuation model for precious opals. Gemval releases a diamond valuation service online.


Gemval serves 1500-2000 users per day worldwide. We undertake work for gem cutters, online gemstone dealers, auction houses, private collectors, consulting institutions and governmental organizations. We now count among our partners and customers:

- Price Waterhouse Coopers

- The World Trade Center

- Jewelry Television

- The International Gem Society

- The US Department of Homeland Security

- The Australian Government

The valuation of every Gemstone is important, We offer the very latest up to date valuation, this enables everyone  to see the  “Average Retail Value” of the gemstone.

With Gemval we as a company, and you the customer, are assured that the valuation is current for the particular month of the year of the valuation.