The four precious stones are from highest to lowest, diamond, emerald, ruby and sapphire. All other gemstones are semi-precious. What distinguishes these four gemstones from the others? It’s their rarity and their quality. They are all translucent with fine colour in their purest forms and their hardness ranges from 8-10 on the Mohs scale.
A diamond is made of pure carbon, and it is the hardest naturally occurring mineral. It is renowned for its scintillation, durability and rarity. Most diamonds are colourless, coloured diamonds are extremely rare and valuable. In fact coloured diamonds are the most valuable substances known to man. Diamond is the birth stone for April.
Most emeralds are highly included, so their resistance to breakage is classified as poor. It is rare to find an emerald that does not have these inclusions. That is why top quality natural Emeralds will often be more than a top quality diamond of the same weight. Emerald is the green variety of Beryl. Emerald is the birth stone for May.
Rubies are extremely strong, they are only slightly softer than diamonds. It is a variety of the mineral Corundum, and their rare hue comes from traces of the mineral Chromium. Although not as flawed as emeralds, almost all rubies are flawed. Most natural rubies are treated to improve their colour and strengthen them. Ruby is the birth stone of July.
Sapphires come in a rainbow of colours varying from blue, yellow, pink, purple, orange, green and black. They also belong to the mineral family known as Corundum. They are the second strongest natural gem stone in existence. Most natural sapphires are heat treated to improve their colour and clarity. Sapphires are the birth stone of September.