Many diamond grading reports are written in American English, so you will see color rather than colour, jewelry rather than jewellery and center rather than centre. The meaning is the same; only the spelling and a few terms differ, and once you know them the report reads easily.
In short: the grades are international, the spelling is American, and a handful of words such as prong, karat and center stone have British equivalents.
Why reports use American spelling
Several of the best known grading laboratories were founded in the United States, and their reports follow American spelling wherever they are issued. Other laboratories in Europe and Asia may use British or international spelling. The grading scales themselves, such as the colour scale from D downwards and the clarity scale from Flawless to Included, are used in the same way whichever spelling appears on the page.
Words you will see and what they mean
- Color: colour. The grade describes how colourless a white diamond is.
- Center stone: centre stone, the main diamond in a ring.
- Prong: claw, the small metal tips that hold the stone.
- Karat: the purity of gold, written carat in British English. A diamond's weight is written carat in both.
- Jewelry: jewellery.
- Gray: grey, sometimes used to describe a tint.
- Millimeters: millimetres, used for the measurements of the stone.
Some reports also use the word fluorescence, describing how a stone glows under ultraviolet light, and terms such as polish and symmetry, which are spelled the same in both forms of English.
Photo: Anthony Shkraba via Pexels.
Reading the measurements
The measurements line usually gives the length, width and depth of the stone in millimetres. For a round diamond it shows the smallest and largest diameter, then the depth. For fancy shapes such as ovals and pears it gives the length and width. These figures tell you how large the stone will look on the hand, which can matter more than the carat weight alone.
Natural and lab-grown reports
Reports for lab-grown diamonds use the same grading words, and they state clearly that the stone is laboratory grown. Some include an inscription on the girdle, readable under magnification, that matches the report number. If you are comparing a natural and a lab-grown stone, check that both reports come from laboratories you trust, as grading standards can vary.
Other terms on the report
Clarity characteristics may be listed as feathers, crystals, clouds or needles, which are names for different kinds of inclusion. A plotting diagram shows where they sit in the stone. Cut grades such as Excellent or Very Good apply mainly to round diamonds. Comments at the bottom of the report may note extra details, such as an inscription or minor characteristics not shown on the plot.
Asking for help
If a word on a report is unclear, ask your jeweller to go through it with you. A good jeweller will explain each line, show you the stone under magnification and point out any inclusions. Our page on diamond carat covers weight in more detail, and our guide to choosing a diamond by dimensions explains how to read the measurements line.
Keep the report safe with your insurance documents. It is a useful record if the ring is ever lost, damaged or needs to be valued.
Frequently asked questions
Why is my diamond report in American spelling?
Several leading grading laboratories were founded in the United States, and their reports follow American spelling wherever they are issued.
Is a prong the same as a claw?
Yes. Prong is the American term for the small metal claws that hold a stone.
Is karat the same as carat?
Karat in American English describes gold purity. Carat describes the weight of a diamond in both British and American English.