I'm wanting to create a variant of the Fabricate spell that can transmute one type of materials into something of a similar type. An example would be turning 500 Gp into one pound of mithral or 1,000 Gp worth of smaller gems into a diamond of similar value.
The spell would only be able to transmute items of the same classification, such as minerals into other minerals, metals into other metals, etc. For reference, this transmutation would be permanent.
I'm not sure what level such a spell would be and would be grateful for any assistance on the matter. If need be, I am willing to put a cap on the amount of matter transmuted per casting of, say, 10,000 Gp.