As far as I know, this isn't an option yet. But it would be interesting to be able to add holdings in precious metals as a separate assets account that automatically updates.

Example:

I buy 100g of silver with my credit card for €60. This becomes a transfer of €60 from my credit card account, resulting in an increase of 100g in the silver account.

The precious metals account would then update in the same manner as currencies.

Thoughts?