Coloured gemstones have been a source of fascination for centuries and their importance is ever-growing. Yet compared to diamonds, coloured gems are considerably more complex to evaluate and understand. The 4Cs for diamonds are well known, but how can one assess the beauty, quality and attractiveness of coloured gems in a competent, comprehensive and yet easily understandable manner?
So far, there was no common language to uniformly assess coloured gemstones. Now the Gübelin Gemstone Rating offers orientation, more transparent information and comparability for final customers as well as the entire industry.
The assessment is based on a point system that is comprehensive while still easy to understand. The system is inspired by wine ratings, which also often express the quality grade of a wine as a point value. High-quality coloured gemstones which receive at least 75 out of 100 possible points qualify for the Gemstone Rating. This number conveys the assessment of the gemstone to jewellery customers, collectors, investors as well as dealers, jewellers and auction houses at a glance.
Quality, rarity and salience
Three factors are examined: quality, rarity and salience. The key factor is quality, in which visual aspects such as colour, clarity/transparency and cut are rated. Rarity includes the type of gemstone, its weight as well as any treatments it might have been subjected to. Salience describes the uniqueness of the coloured gem, its ability to stand out from the crowd. In order to reduce the degree of complexity, gemstone experts use these parameters to calculate a point value that embraces the beauty, attractiveness and rarity in one number: the Gübelin Points.
Along with orientation, the Gübelin Points also offer comparability of coloured gems and assists in making more objective purchasing decisions. This leads to increased trust and security.
Raphael Gübelin, President of the House of Gübelin, explains: “The more you know about coloured gems, the more you value them. With the Gemstone Rating and Gübelin Points, we offer more transparency, comparability and orientation. This benefits everyone buying or selling coloured gems.”
In addition, coloured gems are assigned a designation based on their Gübelin Points rating as “exceptional” (97.5-100 points), “outstanding” (95.0-97.4 points), “excellent” (92.5-94.9 points), “superior” (90.0-92.4 points), “fine” (85.0-89.9 points), “good” (80.0-84.9 points) or “fair” (75.0-79.9 points).
The Gübelin Gemstone Rating was developed for high-quality natural coloured gemstones such as rubies, sapphires, emeralds as well as padparadscha sapphires, paraiba tourmalines, spinels and numerous further varieties of precious gemstones.
Initially, each Gemmological Report from the Gübelin Gem Lab will include a Gemstone Rating free of charge (instead of the regular price of 100 CHF for a Gemstone Rating in combination with a Gemmological Report). A Gemstone Rating on its own costs 250 CHF. The Gübelin Gemstone Rating is currently available from the Lucerne laboratory.