Interactive online gem appraisal model

What do we do?

To provide you with the most accurate online appraisal possible, we have created a sophisticated mathematical model specifically designed to evaluate gems. Each appraisal is based on a complex statistical analysis of current web selling prices for colored gems. The database also takes into account the factors influencing a gem's price such as weight, color, clarity, cut, shape etc. Our specialists collect statistical market data by examining hundreds of lots from different online gem sellers every day. Please be aware that the pricing model parameters (price coefficients) are 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 list of online gemstone resources is continuously growing. We thoroughly check and categorize each online resource before we assign it to our dependency index. We make sure that only market-balanced offers are entered into the database. All specimens with highly irregular prices are rejected and have no impact upon statistical coefficients.

Professional online 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 faceted gemstone may be approximated by the following formula:

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

Where

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).

For each gemstone type, the values of relevant coefficients are derived by the Least Square Method. Currently our statistical database contains over 70000 records; as a rule we upload new records to our database and recalculate coefficients monthly.

Gemstone appraisal  

Value charts