How to choose a ruby
Colour matters most: a pure red with a slight purplish tint is valued above an orangey or overly dark stone. Look at the stone in daylight, not only under a showcase lamp — warm artificial light flatters any red.
Rubies almost always have inclusions, and that is a sign of natural origin. What matters is that they do not reach the surface or cross the centre of the table.
Heating, glass filling and synthetics
Most rubies on the world market are heated — acceptable as long as it is disclosed. Lead-glass fracture filling, however, sharply reduces value: such a stone is damaged by ultrasound, acids and even repair heat.
Synthetic rubies have been grown since 1902 and are indistinguishable by eye. The difference shows only in inclusions and growth lines under the microscope, which is why every stone in this section is lab-checked.