Tanzanite is a blue-violet variety of the mineral zoisite. It is named after Tanzania, where it was discovered. It stands out because of its “trichroism”, which means it appears to change colour from blue to violet when turned in the light. 

This gemstone is the birthstone for December and makes a wonderful birthday gift for those born in mid-winter. This seems a particularly appropriate month for a gem that glimmers in icy blue hues. Tanzanite is also the gemstone gifted on 24th wedding anniversaries.