Gübelin Gemstone Rating

The rating comprises the three domains of quality, rarity and salience. Quality describes the colour (hue, tone, saturation and homogeneity), the clarity and transparency of the gemstone as well as its cut and brilliance. Rarity considers the type of gemstone, the presence, absence or type of treatment, and the weight of the gemstone. Origin is not included in the rating. Additional points are granted for phenomenon and trade colour calls. Salience addresses the extent of exceptionality of a gemstone, it is best seen as the gemstone’s capability to stick out of the crowd.

The world of coloured gemstones is a massive space. It consists of dozens of mineral species, hundreds of varieties, all imaginable hues and shades of colour, and a vast range of different gemmological and aesthetic traits and qualities. Treatments and origins multiply the complexity, as do gemmological phenomenon and certain local and regional preferences. To cope with this complexity is a challenge for professionals, and it is unmanageable for most privates. This makes coloured gemstones a demanding luxury purchase. The end consumer depends heavily on expert’s advice, and it is quite impossible to get even an approximate value-for-money. With the rating system, we intend to quantitatively assess some of the key characteristics of this space, and reduce the complexity by concentrating to a single figure. Thanks to this focus, the Gübelin Points give orientation in the complex world of coloured gemstones.

Our rating system covers the upper part of the coloured gemstone realm. Low-value gemstones, very commercial qualities, crystals, rough gemstones, translucent to opaque gemstones, stones subjected to heavy treatments and synthetics are out of scope. The rating system is designed to handle the specific properties of the more high-end gemstones. To reflect that focus, the range of points is scaled to 75 to 100.

In connection with a report from a respectful gem lab, the Gübelin Points help to find the price. The rating system alone does not consider all aspects that influence the commercial value of a gemstone.

The country of origin might have an ambiguous influence on the rarity or value of a gemstone. Historically, certain origins get related to superior properties such as a favourable colour. Examples of this are rubies from Burma, sapphires from Kashmir, and Colombian emeralds, which developed into actual brands and demanding a premium for their provenance. But such origin branding is controversial, and has hindered top qualities of gemstones from more recently discovered countries, lacking famous pedigree, to get the appreciation they deserve for their beauty and quality. Another ambiguity related to country of origin is the increasing importance of ESG criteria, referring to environmental, social and governance standards that are pursued differently in different places. For these reasons, we have decided to omit the country of origin as a characteristic for the gemstone rating.

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

To our knowledge, there is no comprehensive and easy-to-understand rating system for coloured gemstones in place. Especially consumers, but also the trade is looking for orientation into the complex world of coloured gemstones. With our almost 100 years of experience in seeing the best gemstones of the world, we believe we have a very robust base to establish such a system. Our gemmological laboratory has the credibility and the independence to offer the rating service. This rating service is open to the entire gem and jewellery industry. In a more digital world a rating makes it easier to select the right stone and allow a better comparison, even without having the gem in front. That helps the trade and the consumer.

Our rating system combines comprehensiveness with simplicity. The system is fairly exhaustive regarding the visual quality of a gemstone, and it addresses the main aspects of rarity, another key trait of any gemstone. And finally it includes salience to express the exceptionality or appeal of a stone. All these key aspects are boiled down to one figure. This clarity of our rating system is unprecedented and awaited for specifically by consumers.

Since some years, the industry is already undergoing a change. Standardisation, formalisation and virtualisation are the response to changing expectations and habits of consumers. The current limitations to travel have only accelerated this trend. Our rating system is one tool that will help the industry to keep abreast with this development. It helps communicating within the trade, and with the final customer.

The rating is also available without a report from the Gübelin Gem Lab. However, in combination with a Gemmological Report a gemstone has the best in class overall assessment, which allows for the highest peace of mind for the buyer.

Points are ideal for rankings and assessments, think of school grades or wine ratings, as they provide comparability and give orientation in a comprehensive way. The late Dr Eduard J. Gübelin was known in the industry as an outstanding scientist, and he was equally admired by end consumers for his ability to communicate the beauty of gemstones to clients, explaining to privates how gems formed, and what makes them rare and exceptional. He combined scientific vigour and accuracy with a strong sense for the aesthetics of gemstones. When developing the rating system, we were also very much referring to the descriptions and texts of Dr Gübelin. Hence, the term “Gübelin Points” is not primarily referring to the Gübelin Gem Lab, or the House of Gübelin, but honouring the life and work of Dr Eduard Gübelin.

The rating system is based on a range of different criteria that get reduced to a single number. This implies that several paths can lead to a specific number. A less perfect, but rare stone might get the same points as a more abundant stone of higher quality. Even two gemstones of the same type, size, and treatment might get the same rating, although they look different: one might have a higher rating in colour, which the other compensates with a better clarity or cut rating.

The rating system is based on the wealth of data the Gübelin Gem Lab has gathered on coloured gemstones over its almost 100 years of history and experience. This unique source of knowledge has allowed us to build the required structure and process to perform the rating with the best possible reliability and consistency. Our gemstone experts have to follow a strictly standardised procedure, supported by sophisticated tools and software for the assessment and evaluation of each rating criteria. This reduces the risk of a personal preference of the grader to a minimum. As with all services provided by the Gübelin Gem Lab, the client’s name gets removed from the gemstones before reaching the experts, i.e. they have no knowledge of the identity of the client, as this could also induce a possible bias.

No. It is important to understand that Gübelin Gemstone Ratings are not based to the same level of scrutiny as Gübelin Gemmological Reports. In absence of a Gemmological Report, Gemstone Ratings are done on the basis of a short visual and microscopic assessment only, which does not comply with the standards specified by the Seal featured on Gübelin Gemmological Reports. Owed to this difference, the result of the short visual assessment applied for the Gübelin Gemstone Rating, and hence the resulting Gübelin Points, might not be consistent with the findings stated in a Gübelin Gemmological Report for the same gemstone. This is also why the Rating Document does not show the usual hallmarks of a Gübelin Gemmological Report, such as the hourglass background, signatures and the Gübelin Gem Lab Seal.

The Gemstone Rating considers criteria such as rarity that are potentially undergoing change over time. This is best exemplified on rarity, which is directly influenced by supply and demand. Mining activity and the quality of mined stones changes, as do customer’s preferences. Consequently, rarity parameters need be observed, reviewed and possibly adjusted from time to time. The crux will be to find a balance between stability and consistency of the service on one hand, while reflecting the reality of the market (supply, demand, long-term trends) on the other hand. However, we do not intend to reflect fashions and short-term trends in our rating system.

The reason for not including origin as a characteristic in the Gemstone Rating is due to the ambivalence of origin, as explained in another Q&A (Why is origin not considered). Despite this, we acknowledge that provenance, and specifically country of origin, of a gemstone continues to be of importance for the industry and the end consumer. This is why the Gübelin Gem Lab, continues offering country of origin determination on its Gemmological Reports. In addition, the technologies and services offered by Provenance Proof allow for an even more detailed insight into the exact provenance of a gemstone. With the Provenance Proof Blockchain, we can even provide a tamperproof history along the entire value chain, from the mine to the retail desk, free of charge, and for all types of gemstones and jewellery materials.

The world of coloured gemstones is vast and complex. Moreover, each gemstone is unique, no two gemstones look the same, or are the same. This is what makes them so coveted among professionals and consumers. Gemstones always have defied commoditisation, luckily. But this heterogeneity and complexity also makes it difficult for end customers to get orientation. Our Gemstone Rating attempts to give direction, by reducing complexity. Therefore, the rating system cannot tell the full story of a gemstone, and it cannot exhaustively explain the beauty, appeal and rarity of a gemstone. It is best seen as complementing and enriching the story telling, rather than substituting it.

Since its establishment in 1854, the House of Gübelin had different activities. It started with selling and repairing watches, and later on, Gübelin enriched its assortment with jewellery. When Gübelin started to create their own jewellery, they wanted to know exactly what they buy and what they sell to the clients. At that time, knowledge about gemstones was rather limited to academia and not easily accessible to the industry. To learn more about gemstones and to maintain the trust of its clients, Gübelin set up a gemmological cabinet, one of the first gem labs. So Gübelin opened in 1923 its gem lab, initially doing in-house gemstone testing for their own jewellery only. These early beginnings developed into true gemmological expertise and eventually the internal lab started offering gem testing services to auction houses and to the trade. At this point, Gübelin decided to spin off these activities into its own company, a separate legal entity, to cope with any conflict of interest. This allows the gem lab to remain independent and offer the required privacy to its clients. Since many decades, we have systems and processes that make sure that all stones, regardless who submitted them, undergo the same process of testing, and the same evaluation. The client names and all other client-related information get removed before it goes into the testing process, to reduce the risk of bias. We have very robust systems in place to make sure that our experts see nothing but the stone when doing their work. Nevertheless, the gem lab is a proud member of the Gübelin family, and we are indeed cooperating in certain fields, but definitively not when it comes to the testing, or now the rating of gemstones. The Gübelin Gem Lab acts independently in its lab activities, and is not subject to any influence when it comes to testing gemstones, nor do we give any privileged insight into stones and orders we are getting.
We are very much aware of the challenges that come with the group structure, and since decades we are used to manage and maintain the required separation of systems, data and responsibilities. It is this commitment to independence which ensures the provision of unbiased services, and the privacy and discretion of client’s data. This is the very basis for the trust we have earned over time in the trade and the public.

Traditionally, the interpretation and explanation of quality, beauty and rarity was with the trader or the jeweller. Beauty is an essential aspect for coloured gemstones and one central characteristics to define them. In general, beauty is in the eye of the beholder, and no one can tell you what you personally consider beautiful. But as beauty, and even more so quality, is also a powerful lever of value and price, the common and professional definition following certain logic and rules.

Gem labs have mainly focused on the aspects that are based on scientific, analytical methods, focussing on the material properties of the gemstones. Traditionally, gem labs master these science-based technologies, and have permanently pushed their use to novel applications. Our understanding of technologies has also enabled us to tackle new challenges, such as bringing transparency in the supply chain of gemstones. This resulted in new services, the Emerald Paternity Test and the Provenance Proof Blockchain, see www.provenanceproof.com for more information on these ground-breaking developments.
And now, we are again using technologies and data to address another challenge related to gemstones: giving end consumers orientation and direction in the complex world of coloured gemstones. On the basis of decades of seeing the most exceptional gemstones of the world, we have built a fairly comprehensive system and method to assess the aspects of quality, rarity and salience in a structured and reproducible way. By reducing these aspects into a single number, the Gübelin Points, we convert a highly complex topic in an easy-to-understand benchmark figure. This rating system shifts some of the power of interpretation from the trade to the end consumer. We believe that such empowerment of the final client gives them confidence, and hence is helpful for the wellbeing of our industry. And we also believe that a gem lab, an entity not involved in the transaction of a stone, is well positioned to rate beauty and rarity of a specific gemstone from a more neutral standpoint.

While beauty is indeed in the eye of the beholder, one can identify some general assumptions about the perception of beauty in gemstones. Instead of tackling beauty directly, we address quality and salience. By looking at our data gathered over many decades, the perception of quality seems to be based on a set of stable principles. As with all principles, there are exceptions, as they do not consider regional and local deviations, leave alone personal ones. Likewise, fashion and trends are also permanently shifting these principles. Nevertheless, by observing the gemstone industry over many decades, and having the privilege to get to see many of the high-value gemstones in the trade, we have identified some principles or rule of thumbs that we consider valid long-term, and globally. Among these are the perception that the higher the transparency of a gemstone, and the less eye-visible inclusion present in the stone, the higher its quality. The more equal and homogeneous the colour is distributed over the stone, the better. And the more saturated and vivid a colour (i.e. saturation and hue being in harmony), the better (one popular exception of this principle are padparadscha sapphires, where pastel colours are preferred over saturated ones). Other characteristics have an optimum, such as size, where bigger stones are rarer and seen as more valuable as small stones, but once the stone becomes oversized, it might not get much of a premium for this extra-weight. Naturally, the rating of size depends on the type of gemstone, i.e. a ruby of 8 ct is considered rarer than an aquamarine of 8 ct. Other characteristics, such as hue, might not have a singular ideal, but allow for a certain breadths. For example, topazes of different hues, such as red and orange, can be seen as equally valuable and coveted. In general, the straight hues are considered more desirable than hues with a modifying colour (padparadscha again being a well-known exception, demanding a blend of both pink and orange hues).

Compared to quality and rarity, salience is the parameter with the least quantitative or scientific base. It contains an element of subjectivity, but it is based on a common perception. When defining the quality criteria, we realised that some gems show properties that are not exactly matching the parameters of a defined ideal, but which are highly attractive. And there are also some gems that fit well to what is considered as to be ideal, but they lack of charm or appeal. There seems to be a common consensus among gem connoisseurs about which gemstones – beyond the objective quality criteria – are highly attractive and “talk to them”. This shared perception made us introducing salience. It allows, for example, to compensate for the lower transparency rating that the typical Kashmiri sapphire with the velvety appearance will get. Or for the lower rating for colour homogeneity in the most beautiful padparadschas that typically show a slightly uneven colour distribution. And it also allows to compensate for a stone that ranks high in the more objective parameters addressed in the quality and rarity domains, but lack appeal. Salience might be subjective to a certain extent, but it is not random.

Information is key to judge a gem. Our range of innovative services and technologies can be combined to gain more information about different aspects of a gemstone and to get a bigger and better picture. These services compliment and enrich each other to get a deeper understanding of gemstones. The Gemmological Report offers a science-based opinion about the identity, authenticity and origin of a gemstone. The Gemmological Profile is a more comprehensive document, elaborating on the somewhat encoded wording used on gem lab reports, and providing additionally background information on the type of gemstone, its geological history as well as individual images of the gem’s inner world. It also contains analytical details and an insight into the microscopic, chemical and/or spectroscopic data the experts at the Gübelin Gem Lab have gathered on that specific stone. Both documents do not judge on quality. This is what the Gemstone Rating does. The overall rating of the gem’s quality, rarity and salience is expressed in Gübelin Points which offer orientation and comparability to everybody who sells or buys gemstones. While the combination of these services complement the description of a stone, they cannot exhaustively explain or communicate its value, beauty and individuality. In addition, the Provenance Proof initiative (see www.provenanceproof.com for details) offers a range of services, deploying the most cutting-edge technologies, to provide transparency into the exact provenance and the entire supply chain.
Our overall aim is to offer a broad and comprehensive range of information that allows the buyer to make a conscious purchasing decision based on reliable data from a trustworthy source.