Stonework is the gift given originally to the dwarves, and gives the ability to shape, work and use stone for various purposes. This includes both fine work such as working gems, right up to the ability to create large stoneworks like castles.
Stonework is used by humans, giants that aren’t stone giants, and gnomes. While it has not become an extremely popular gift, stonework is in demand, both for building materials made of stone, and the cutting of gems for currency, so that just leaves plenty of space for dwarves to do the work.
Combined with architecture, stonework allows stone buildings.
Combined with economics, stonework allows currency made from gems.