Gübelin has developed an innovative rating system aimed at meeting the industry’s need for a universal language to evaluate coloured gemstones – the Gübelin Gemstone Rating.

According to the company, the assessment is made using a comprehensive yet easy-to-understand point system where high-quality coloured gemstones are given at least 75 out of 100 possible points.

Using special parameters, a gem’s beauty and rarity are expressed in a single number: The Gübelin Points.

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).

Raphael Gübelin, president of the House of Gübelin, explains the pertinent components of the Gübelin Gemstone Rating system.

JNA: Please walk us through the process of having a gemstone tested using this new rating system. How does it work exactly?

Raphael Gübelin: There are two ways to acquire a gemstone rating. You can either get it in combination with a Gemmological Report or order it as a stand-alone service. Experienced and trained gemmologists perform the rating following a highly standardised assessment procedure. Factors such as quality, rarity and salience are examined. The main factor, quality, consists of different parts: Colour, clarity/transparency and cut/brilliance. Colour is further divided into hue, tone, saturation and homogeneity. Rarity comprises the type of gemstone, the absence or presence of treatment, the type of treatment, and the size of the gemstone.

Finally, salience addresses the level of exceptionality of a gemstone and how it is able to attract the attention of the observer. The overall result of the rating is expressed in easy-to-understand numbers: The Gübelin Points. This rating is done in our Lucerne laboratory. The client will receive the rating document, including the Gübelin Points as well as the matching designation.

To perform the rating, the identity (species, variety), the weight, the presence and type of treatment, and possible gemmological phenomena and presence of a trade colour need to be determined. This information can come either from the accompanying Gübelin Gem Lab report, or, if absent, it gets determined in the lab by means of an informal assessment. Once these factors are known, the remaining eight parameters of the quality and salience domain get assessed by gemstone experts, applying a highly structured procedure based on the data of several tens of thousands of gemstones we have seen over the decades. The individual rating parameters are then weighed and consolidated into their respective group and domain rating, and finally expressed in the total Gübelin Points.

JNA: Could you expound on the rating system's digital component?

Raphael: The Gübelin Gemstone Rating provides a novel system that expresses beauty, rarity and exceptionality of a gemstone in a single number. This will enable a new and convenient way of communication, and as such, contribute to the feasibility and acceptance of digital trading and retailing. The Gübelin Points will provide a way to assess the gemstone, especially when it will be sold online.

JNA: The coloured gem sector is highly fragmented, with no universal testing standards. How is the response to this new service?

Raphael: We expect that a significant share of the trade will recognise the advantages of having key features of a gemstone expressed in a single number, comparable to Parker’s wine rating system. These early adopters will be better positioned to offer their products digitally to their clients in the industry and ultimately, the end consumer. End buyers expect to make autonomous and informed purchasing decisions, and to rely less on experts. The Gübelin Gemstone Rating will help end consumers understand and value coloured gemstones better, so they feel more comfortable to buy them. This will popularise coloured gemstones and help the entire gem and jewellery industry. So far, we have received a lot of positive feedback. Many people appreciate more orientation, trust and comparability in purchasing coloured gemstones. The most enthusiastic reactions we received came from Asia, and from younger stakeholders.

JNA: Which gems fall under the high-value group?

Raphael: The rating is offered for most coloured gemstones of higher value, including ruby, blue and Padparadscha sapphires; emerald, spinel (red-pink), alexandrite, chrysoberyl, Paraiba tourmaline, rubellite, indicolite, tanzanite, aquamarine, morganite, heliodor, demantoid, tsavorite, mandarin garnet, imperial topaz and red-pink topaz. These types of gemstones qualify for the Gübelin Gemstone Rating as long as they are natural, transparent and faceted or polished.

JNA: Does it also cover provenance?

Raphael: Origin is not taken into consideration. The country of origin, and its meaning and relevance for the end consumer is a highly controversial topic, and difficult to address in a general rating. For this reason, country of origin and provenance is excluded from the rating for the time being. However, these are available by means of standard gemmological reports, and modern tracking and tracing systems such as the ones available from Provenance Proof. The Gübelin Gemstone Rating with the Gübelin Points can be stored on the Provenance Proof Blockchain.

JNA: How will it impact the trade's quest for transparency and traceability?

Raphael: It makes coloured gemstones more understandable. It offers more transparency in how to consider the beauty and rarity of gemstones – two important but highly complex parameters. Of course, beauty is in the eye of the beholder. But beauty is also a powerful lever of value and price, following certain logic and rules. To know about this interpretation of beauty, and hence the application of these rules, was so far exclusive to industry and trade experts. The rating system is an important step to help understand how beauty and rarity of gemstones are interpreted and assessed, and ultimately how they relate to value. It also offers more information to traders and jewellers that they can explain and present to their clients. In general, the rating system empowers coloured gemstone traders to make more informed buying decisions.