the core book contains rules for storing vis in normal objects. An object can hold as much vis as the Size and Material allows.
Can you store different types of vis in an object? e.g. I have a gold ring (10 * 1 = 10 pawns) and I put into it 5 pawns of Terram and 5 pawns of Ignem.
Can you use the rules for a composite object? e.g. a gold ring with a diamond and a saphire.