You can choose a stone based on many factors. Some factors can be color, shape, weight, purity, etc.
1 -Your colour
Colour is one of the most important aspects of gems, so this often results in the choice of a gemstone.
Some Burmese rubies are described as: "Dove Blood," this exceptional red colour is very precise in the eye of the specialist but has nothing to do with the colour of the animal's blood. It is for all precious stones, the colour is paramount and can define certain provenances: for Star Sapphire: Kashmir blue, Burma blue, Ceylan blue.