Jewellery Glossary Terms

Akoya Pearls:

Akoya PearlsPearls from the Akoya saltwater oyster which is the mainstay of the Japanese pearl industry. Now also farmed by China and other countries.


Bullion An alloy is a combination of two or more metals. Common alloys used in jewellery and giftware in the UK & Ireland are: Gold 9ct (37.5% gold with varying amounts of other metals such as silver depending on colour and other characteristics wanted) Gold 18ct (75% gold), 22ct (91.6% and very soft); Platinum (95% platinum); Silver Sterling (92.5% silver); and Pewter (92% tin with lead, antimony and a bit of silver or copper).

Baroque Pearls:

Irregular shaped pearls of all shapes and sizes, neither round nor symmetrical. The surface is usually uneven. Most are inexpensive, but some have come to be the centrepiece for very expensive pieces of jewellery.

Biwa Pearls:

Cultured freshwater pearls grown in Lake Biwa in Japan.


A stone cut with a domed top and a flat bottom. These are usually round or oval.


A unit of weight measurement for precious stones. It is important not to confuse this with the other karat (American spelling) or carat, which is a measure of the purity of gold. 'Carat' is abbreviated to "ct." One carat is equal to 1/5 of a gram (200 milligrams). Stones are measured to the nearest hundredth of a carat. There are a hundred points in a carat, so that a .10 carat stone can also be described as a 10 point stone. Smaller stones are most often referred to by point designations.An average one-carat round diamond usually measures approximately 6.5mm in diameter. This relationship of weight and size, however, is different for each type of cut and differs for other gems. Rubies and sapphires, for example, are both heavier than diamonds, so a one carat ruby or sapphire is smaller in size than a one carat diamond.