Like diamonds, coloured stones proposed by the Private Diamond Club are set so that they reflect as much of the light they have absorbed as possible.

Rubies mainly originate from Burma, Siam and Ceylon. Their rarest variety, the 'Pigeon's Blood', pure red with a hint of blue, can reach several times the value of diamonds of the same weight.

Sapphires are extracted from the mines of Cashmere, Burma, Ceylon, Australia, Thailand and Cambodia. The most sought-after sapphire has a colour that resembles that of cornflower : royal blue, neither too light nor too dark.

The finest and rarest emeralds originate from Colombia, but also from Brazil, Rhodesia, the Transvaal, the Ural and Pakistan. The numerous inclusions of emeralds, their "garden", do not affect their value and attest to their authenticity.