BOOK A VIRTUAL APPOINTMENT CALL 0207 493 0714 NOW!
Start typing to see products you are looking for.
  • Pages Pages
  • Jewellery Jewellery

Shopping cart

Close
Menu
close
Start typing to see products you are looking for.

Jewellery Advice and Knowledge Jewellery Advice and Knowledge

Jewellery Advice and Knowledge Jewellery Advice and Knowledge

Are coloured stones graded? Are coloured stones graded?

We have a fantastic collection of coloured stones; sapphires, rubies, emeralds, aquamarines and tanzanites and they are often popular choices for engagement rings or anniversary jewellery. However, it has become clear that many of our customers are uncertain as to how coloured stones are certified. It is often assumed that they are graded in the same way as diamonds, but this is a common misconception as they are not. They can indeed be certified, but the criteria is somewhat different. Read on to explore how!

Coloured stone certificates

For certification of a coloured stone, a laboratory will provide most, if not all, of the following information:

  • Dimensions 
  • Carat weight
  • Image of the stone
  • Cut
  • Shape
  • A description of colour 
  • Geographical origin
  • The presence and extent of any treatments.

Here is an example of a sapphire certificate by Gūbelin, possibly the premier coloured stone certifying body:


Notice that there is no clarity grade. Whilst a clean stone is still sought after, inclusions are more likely to be present within coloured stones than diamonds, so it is not assessed.  Unlike the ‘4 C’s’ for diamonds, where coloured gemstones are concerned there are two main reasons why you may want a certificate: to confirm the geographical origin of the stone and whether or not there is evidence of any treatments.

If the gemstone is not from a particularly desirable location, and has received treatment, it will most likely not be certified - these are the vast majority of stones, and there just is little point to it. Rather than specifying which coloured stones are treated, it’s usually the other way around - you can safely assume that it has been treated unless specified otherwise. But this doesn't mean that it's a poor quality stone! Those gems that are from key areas and/or untreated are extremely rare and expensive. It is possible to find exceptional stones from unusual locations, or poorer quality stones with excellent origins. The most important thing is that you like the colour and tone of the stone.

Geographical Origin

There are certain geographical locations where stones are particularly sought after as they are deemed to be of a higher quality and more desirable colour. For example, Burmese rubies, Colombian emeralds and Kashmir or Ceylon sapphires, most of which probably sound familiar to you. A certificate will commonly state the geographical origin of the stone, as they assess the chemical structure of the gem and identify specific geological characteristics which they are able to attribute to it having come from a specific place. These locations command a premium, so it is worth having it on paper. 

Here is an example of a sapphire GIA certificate, or "Origin Report":


Presence of treatments 

The second key reason you may want a coloured stone to be certified is to confirm that it has not received any treatments. The vast majority of sapphires, emeralds and rubies that you will see on the market will have been treated in some way, and these are deemed acceptable and do not reduce a gemstone’s value. For rubies and sapphires, it is predominantly a heat treatment used to even out colour or enhance clarity. For emeralds, it is common to receive an oil treatment to enhance clarity. However, if your chosen stone is naturally a very high quality and has not needed any of these very common treatments, they are relatively rare and unique and therefore will be much more expensive. Certification will identify the presence, and extent of, treatments and you will definitely want confirmation from a laboratory certificate to justify the higher price of an untreated stone. 

For example, see the ruby certificate below. In the comment section it says "H(a)", and on the reverse of the certificate (the second image) you will see a Key of terms. Here it describes H(a) as "Enhanced by heat, residue insignificant."

 

What about the AAA system?

You may have heard of coloured gemstones being classed as AAA, AA, or A grade. This is a system used by some dealers and wholesalers in an attempt to create a standardised system to classify coloured stones into clearer, more distinct categories, in a similar way to diamond grading. This is predominantly to increase the commerciality of the gemstones as it is then easier to sell a stone that fits into a nice, neat category. However, it is not a wholly accepted system. It takes into consideration beauty and intensity of colour, transparency of the stone, quality of the cut, but the requirements are vague and not as clear as the diamond grading system. Consequently, you won’t see an A grade on a GIA certificate (or most certificates, for that matter). 


How do you know that a coloured stone is a good colour and quality?

When you are choosing a sapphire, ruby, emerald or other coloured stone, there are some colours that are deemed to be more desirable, but please do bear in mind that this is highly subjective and largely down to individual taste. You may just prefer a lighter blue sapphire, or perhaps a very dark ruby - and that’s ok! The colours deemed to be ‘most desirable’ are based on the court of public opinion and are generally what most consider to be ‘most aesthetically appealing’ when considering a gemstone. At the end of the day, it is down to your own personal taste (and probably your own budget restrictions to some extent, too!). However, here are some key points to look out for when choosing a coloured stone:

  1. Intensity of colour: this is the saturation. Ideally, you would like a nice rich red, blue, green etc.  
  2. Consistency of colour throughout the stone rather than patches or areas of lighter/darker colour.
  3. The lightness or darkness of the stone. If it is too dark or too light, the colour will be difficult to distinguish.
  4. Transparency: the stone should be transparent enough to enjoy a play of light throughout but not so transparent that it is insipid and weak. Generally, the more opaque a stone the duller the appearance. 
  5. Lower clarity is generally more acceptable in coloured stones than in diamonds. The presence of inclusions in emeralds is widely accepted as part of the package, and it is increasingly unusual to find high quality, large rubies and sapphires that are completely clean. These stones will most likely have received some minor treatment to address these clarity issues, greatly reducing their visibility. This is why there is no clarity grade provided on a coloured stone certificate. 

Hopefully, you have found this to be a helpful introduction to coloured stone certification and can now go forth in your jewellery search armed with the facts. But, if you have any further questions, please do not hesitate to get in touch. We are always more than happy to discuss the ins and outs of jewellery with you!

We have a fantastic collection of coloured stones; sapphires, rubies, emeralds, aquamarines and tanzanites and they are often popular choices for engagement rings or anniversary jewellery. However, it has become clear that many of our customers are uncertain as to how coloured stones are certified. It is often assumed that they are graded in the same way as diamonds, but this is a common misconception as they are not. They can indeed be certified, but the criteria is somewhat different. Read on to explore how!

Coloured stone certificates

For certification of a coloured stone, a laboratory will provide most, if not all, of the following information:

  • Dimensions 
  • Carat weight
  • Image of the stone
  • Cut
  • Shape
  • A description of colour 
  • Geographical origin
  • The presence and extent of any treatments.

Here is an example of a sapphire certificate by Gūbelin, possibly the premier coloured stone certifying body:


Notice that there is no clarity grade. Whilst a clean stone is still sought after, inclusions are more likely to be present within coloured stones than diamonds, so it is not assessed.  Unlike the ‘4 C’s’ for diamonds, where coloured gemstones are concerned there are two main reasons why you may want a certificate: to confirm the geographical origin of the stone and whether or not there is evidence of any treatments.

If the gemstone is not from a particularly desirable location, and has received treatment, it will most likely not be certified - these are the vast majority of stones, and there just is little point to it. Rather than specifying which coloured stones are treated, it’s usually the other way around - you can safely assume that it has been treated unless specified otherwise. But this doesn't mean that it's a poor quality stone! Those gems that are from key areas and/or untreated are extremely rare and expensive. It is possible to find exceptional stones from unusual locations, or poorer quality stones with excellent origins. The most important thing is that you like the colour and tone of the stone.

Geographical Origin

There are certain geographical locations where stones are particularly sought after as they are deemed to be of a higher quality and more desirable colour. For example, Burmese rubies, Colombian emeralds and Kashmir or Ceylon sapphires, most of which probably sound familiar to you. A certificate will commonly state the geographical origin of the stone, as they assess the chemical structure of the gem and identify specific geological characteristics which they are able to attribute to it having come from a specific place. These locations command a premium, so it is worth having it on paper. 

Here is an example of a sapphire GIA certificate, or "Origin Report":


Presence of treatments 

The second key reason you may want a coloured stone to be certified is to confirm that it has not received any treatments. The vast majority of sapphires, emeralds and rubies that you will see on the market will have been treated in some way, and these are deemed acceptable and do not reduce a gemstone’s value. For rubies and sapphires, it is predominantly a heat treatment used to even out colour or enhance clarity. For emeralds, it is common to receive an oil treatment to enhance clarity. However, if your chosen stone is naturally a very high quality and has not needed any of these very common treatments, they are relatively rare and unique and therefore will be much more expensive. Certification will identify the presence, and extent of, treatments and you will definitely want confirmation from a laboratory certificate to justify the higher price of an untreated stone. 

For example, see the ruby certificate below. In the comment section it says "H(a)", and on the reverse of the certificate (the second image) you will see a Key of terms. Here it describes H(a) as "Enhanced by heat, residue insignificant."

 

What about the AAA system?

You may have heard of coloured gemstones being classed as AAA, AA, or A grade. This is a system used by some dealers and wholesalers in an attempt to create a standardised system to classify coloured stones into clearer, more distinct categories, in a similar way to diamond grading. This is predominantly to increase the commerciality of the gemstones as it is then easier to sell a stone that fits into a nice, neat category. However, it is not a wholly accepted system. It takes into consideration beauty and intensity of colour, transparency of the stone, quality of the cut, but the requirements are vague and not as clear as the diamond grading system. Consequently, you won’t see an A grade on a GIA certificate (or most certificates, for that matter). 


How do you know that a coloured stone is a good colour and quality?

When you are choosing a sapphire, ruby, emerald or other coloured stone, there are some colours that are deemed to be more desirable, but please do bear in mind that this is highly subjective and largely down to individual taste. You may just prefer a lighter blue sapphire, or perhaps a very dark ruby - and that’s ok! The colours deemed to be ‘most desirable’ are based on the court of public opinion and are generally what most consider to be ‘most aesthetically appealing’ when considering a gemstone. At the end of the day, it is down to your own personal taste (and probably your own budget restrictions to some extent, too!). However, here are some key points to look out for when choosing a coloured stone:

  1. Intensity of colour: this is the saturation. Ideally, you would like a nice rich red, blue, green etc.  
  2. Consistency of colour throughout the stone rather than patches or areas of lighter/darker colour.
  3. The lightness or darkness of the stone. If it is too dark or too light, the colour will be difficult to distinguish.
  4. Transparency: the stone should be transparent enough to enjoy a play of light throughout but not so transparent that it is insipid and weak. Generally, the more opaque a stone the duller the appearance. 
  5. Lower clarity is generally more acceptable in coloured stones than in diamonds. The presence of inclusions in emeralds is widely accepted as part of the package, and it is increasingly unusual to find high quality, large rubies and sapphires that are completely clean. These stones will most likely have received some minor treatment to address these clarity issues, greatly reducing their visibility. This is why there is no clarity grade provided on a coloured stone certificate. 

Hopefully, you have found this to be a helpful introduction to coloured stone certification and can now go forth in your jewellery search armed with the facts. But, if you have any further questions, please do not hesitate to get in touch. We are always more than happy to discuss the ins and outs of jewellery with you!

SIGN UP AND CONNECT TO MICHAEL ROSE! SIGN UP AND CONNECT TO MICHAEL ROSE!

Be the first to learn about our latest collections and our most exclusive offers. Be the first to learn about our latest collections and our most exclusive offers.

Will be used in accordance with our Privacy Policy

Will be used in accordance with our Privacy Policy

Scroll To Top

#title#

#price#
×