Diamonds occur in many different colours, from pink through to brown, orange and blue. However, most diamonds of gem quality appear on a scale from colourless to yellow. The most intensely coloured diamonds are called ‘fancy’ and there’s an increasing market for them. Colourless diamonds have traditionally been popular, especially for engagement rings and the fewer the flaws within the diamond, the more precious the gem.

Diamonds are rated on a special scale, under magnification so that any internal flaws can be seen. Completely colourless diamonds are the rarest and most expensive - diamonds with flaws become more affordable as the number of flaws increase.

Hallmarks have been used in Great Britain as a form of consumer protection since 1300 AD.

Each symbol stands for something different; one says how pure the metal is, one records the year of manufacture, one records which assay office was used and one records the manufacturer of the piece.

Before a piece of metal can be hallmarked it must be tested (or assayed) by one of the UK’s four assay offices. All precious metals have to be hallmarked by law. There are three compulsory hallmarks:

The sponsor’s mark shows the company who sent the item for testing.

The assay office mark which shows which assay office has tested the item.

The standard mark shows the standard of the precious metal. For silver this is 925 and for 18ct gold it’s 750.

Each UK assay office has its own hallmark:

The leopards head is for London, the anchor for Birmingham, the Yorkshire rose for Sheffield and the castle for Edinburgh.

Since 1478 the hallmark has included a date letter indicating the year of hallmarking - this is unique for each year - when the alphabet has been used the style of the letter changes.

The final mark is the Fineness symbol. This is a traditional symbol denoting the fineness of the metal. It is a lion for silver and a crown for gold.

The H=hallmark for gold is now governed by the 1973 Hallmarking Act.

9ct Gold = 375 parts pure gold out of a 1000
14ct Gold = 585 parts pure gold out of a 1000
18ct Gold = 750 parts pure gold out of a 1000
22ct Gold = 916 parts pure gold out of a 1000
Platinum standard = 950 parts pure platinum out of a 1000