Diamond glossary
Diamond and jewellery terms, in plain language.
The words you’ll see on grading reports, product pages and quotes, explained in everyday language. Use the letters to jump to a term.
From the CTJ Jewellery team, led by founder Greg Ward
A
- Asscher cut
- A square step cut with deep, cropped corners.
B
- Bezel setting
- A rim of metal that surrounds the diamond. The most protective setting.
- Bow-tie
- A dark, bow-shaped shadow across the centre of some oval, pear and marquise diamonds.
- Brilliance
- The white light a diamond returns to the eye.
C
- Carat
- The unit of weight for diamonds. One carat is 0.2 grams.
- Cathedral setting
- A setting where the shoulders rise to support the centre stone.
- Claw
- A small prong of metal that holds a diamond in place. Also called a prong.
- Clarity
- A grade for the number, size and visibility of inclusions and blemishes.
- CAD
- Computer-aided design. Used to plan and visualise a custom piece before it is made.
- CVD
- Chemical vapour deposition. A lab-grown method that builds a diamond layer by layer from carbon-rich gas.
- Cut
- The proportions, symmetry and polish of a diamond that influence its brightness, fire and sparkle.
D
- Diamond shape
- The outline of a diamond seen from above, such as round, oval or emerald.
E
- Eternity ring
- A band set with diamonds partway (half eternity) or all the way round (full eternity).
- Eye-clean
- No inclusions visible to the naked eye at a normal viewing distance.
F
- Fire
- Flashes of spectral colour produced as light splits inside a diamond.
- Fluorescence
- A glow some diamonds show under ultraviolet light. Graded from none to very strong.
G
- GIA
- Gemological Institute of America. An independent laboratory that issues internationally recognised diamond grading reports.
- Grading report
- A document from an independent laboratory recording a diamond’s measurements, grades and origin. Also called a certificate.
H
- Halo
- A ring of small diamonds set around a centre stone.
- Hidden halo
- A circle of small diamonds beneath the centre diamond, adding sparkle from the side.
- HPHT
- High pressure, high temperature. A lab-grown method that recreates the conditions in which natural diamonds form.
I
- IGI
- International Gemological Institute. An independent laboratory that grades natural and lab-grown diamonds.
- Inclusion
- A tiny internal feature inside a diamond, formed as it grew.
K
- Kimberley Process
- An international certification scheme, in force since 2003, for rough natural diamonds traded between countries.
L
- Lab-grown diamond
- A real diamond created in a laboratory, with the same chemical, physical and optical properties as a natural diamond.
- Loupe
- A small magnifying lens used to inspect diamonds. The industry standard is 10×.
N
- Natural diamond
- A diamond formed in the earth over billions of years. Sometimes called a mined diamond.
P
- Pavé
- Small diamonds set close together along a band, held by tiny beads of metal.
R
- RBC
- Round brilliant cut. A round outline with facets designed for maximum light return.
- Rhodium plating
- A bright white finish applied to white gold. It wears over time and can be renewed.
S
- Scintillation
- The sparkle and pattern of light and dark as a diamond moves.
- Solitaire
- A ring set with a single diamond.
- Step cut
- A cut with long, parallel facets, such as emerald and asscher.
T
- TDW
- Total diamond weight. The combined weight of all diamonds in a piece of jewellery.