The silver necklaces worn by the people of Lyria contain a single gem set at the apex. The colour and shape of this gem are determined by the wearer’s status and occupation. The gem worn changes over time in much the same way as a heraldic crest: a marriage, a promotion, an achievement: all are marked by changes in the gem.
A man with a red gem marries a woman with a blue gem. The result is a purple gem whose hue is determined precisely by the hues of the original gems.
The more edges a gem has the higher the class of the wearer, so whereas the aristocrats can afford to wear richly coloured spherical gems, visitors or immigrants to Lyria are forced to wear black tetrahedral (d4) gems.
Thieves and murderers are given leather necklaces with granite stones in place of silver ones with gems.
There is quite an underground trade to be had for nefarious gem-cutters.