We all know the answer is diamond but did you know there is a whole scale dedicated to the rest? Known as the Mohs Scale, it ranks minerals by their ability to scratch each other; #1 being the softest mineral and #10 the hardest. It is an important factor to consider when choosing your jewellery as it can determine what designs suit a particular stone, how to look after them and prevent them from being damaged.
The test compares the resistance of a mineral as it is scratched by ten different minerals, hence the name Mohs Hardness Scale. It is a relative scale, not proportionate, meaning that a mineral with a hardness of #10 will not be twice as hard as a 5.
German mineralogist Friedrich Mohs, who developed the scale in 1812, selected ten minerals of distinctly different hardness that range from soft mineral (talc) to a very hard mineral (diamond).
Mother of Pearl: 2.5-4.5
Ruby and Sapphire: 9
Remember to take this scale into account when picking your next gemstone and by all means ask your jeweller if you are ever unsure.