Let’s remember when it’s smart to keep the equipment simple and affordable. You the designer or jeweler make far more difference than the equipment does.
For torch work in casting hydrogen is far and away the best to actually use. Plenty of heat, and as you dial the oxygen up or down, you never a carbon-rich flame. No carbon at all in hydrogen right? Hydrogen-rich can reduce oxides in alloys with copper. Hello, most every gold karat and color.
Platinum likes clean heat. Lots of it but not too much so as to not compromise the crucible.
Inexpensive induction machines may or may not do as well for you as a good torch. The more expensive centrifugal machines are better than any torch, I admit that freely. But many of you are investing in CAD printers, software, the “Resin Of the Week Club”. Money is always short in the shop. So until your volume demands it, think about hydrogen for your casting heat and alloying.