Lab grown diamonds are assessed by gemological laboratories, but the words on the document are not always the same as those on a natural diamond report. Since 1 October 2025, GIA has used a Laboratory Grown Diamond Quality Assessment that classifies eligible stones as Premium or Standard, rather than the nomenclature it created for natural diamonds.
Why GIA changed its language
GIA announced the change in August 2025, and the new service began on 1 October 2025. GIA’s president and CEO, Pritesh Patel, said that using descriptive terms is appropriate, and that GIA will no longer use the nomenclature created for natural diamonds to describe what is a manufactured product. The assessment looks at clarity, colour and cut as a whole, then gives one overall classification.
This does not mean a lab grown diamond is ungraded. It means a current GIA assessment for a colourless to near colourless lab grown diamond uses Premium or Standard, instead of the familiar D to Z and clarity scale as the headline result. GIA still sets clear minimums behind those two words.
| GIA classification | What GIA requires |
|---|---|
| Premium | All Premium criteria: clarity of Very, Very Slightly Included and higher, colour D, Excellent polish and symmetry, and an Excellent cut grade for round brilliant cut diamonds |
| Standard | The Standard minimums, or a mix of Premium and Standard criteria: clarity of Very Slightly Included, colour E to J, Very Good polish, Very Good symmetry or Good for fancy shapes, and a Very Good cut grade for round brilliants |
| No GIA assessment | GIA says any diamond that does not meet all the minimum criteria for Standard will not receive a GIA assessment |
GIA offers this Quality Assessment for loose, colourless to near colourless lab grown diamonds of 0.15 carats or more. The girdle is laser inscribed with the term Laboratory Grown and the GIA quality assessment number, and a printed document is returned with the stone. GIA also offers separate services for lab grown coloured diamonds. We will not quote laboratory fees here, because those are set by the laboratory and can change.
What this means when you choose a stone
Other laboratories may still describe lab grown diamonds with letter and number grades for colour and clarity. Our note on IGI and GIA lab reports sets out how those documents can differ. The important habit is to read the report that belongs to the actual stone, rather than assuming every lab grown diamond is described in the same way.
We source lab grown and natural diamonds, and we only begin making a ring once you have approved the stone and the design in writing. If you would like help reading a document, start with our guide to reading a GIA certificate, browse our lab grown colourless diamonds, or contact us for a video consultation.
Frequently asked questions
How are lab grown diamonds graded?
They are assessed by gemological laboratories, but the language on the document is not always the same as on a natural diamond report. Since 1 October 2025, GIA has used a Quality Assessment that classifies eligible lab grown diamonds as Premium or Standard, rather than the nomenclature it created for natural diamonds.
What does Premium mean on a GIA lab grown assessment?
GIA says a lab grown diamond is classified as Premium only if it meets every Premium criterion: clarity of Very, Very Slightly Included and higher, colour D, Excellent polish and symmetry, and an Excellent cut grade for round brilliants.
What does Standard mean on a GIA lab grown assessment?
GIA classifies a stone as Standard if it meets the Standard minimums, or a mix of Premium and Standard criteria. The Standard minimums include clarity of Very Slightly Included, colour E to J, Very Good polish, Very Good symmetry or Good for fancy shapes, and a Very Good cut grade for round brilliants.
Do all laboratories use Premium and Standard?
No. The Premium and Standard terms are GIA’s current language for eligible colourless to near colourless lab grown diamonds. Other laboratories may still describe colour and clarity in familiar letter and number grades. We will walk you through the document that accompanies the stone you are considering.