Congratulations on your new opal collection!!! Looks like you have some very nice stones. It's not clear what size any of these cabs are, so it's hard to make any sort of guess as to what type of jewelry would include all of the stones at once (minus the three with cracks that I can see). If it were me, I think I'd go for a couple of necklaces or bracelets. The top stone on the right makes me think of a ring setting (or any of the other stones for that matter). The diamond shape below it would lend itself well as a pendant with some other stones to accent it.
If you have a vision for a killer multi-stone brooch or complex pendant, make some pencil drawings (plural) on tracing paper, which is easier to correct. Bounce those ideas around and give it some time to gel in your mind.
People go about buying gold in a variety of ways. You can buy pre-made settings from jewelry supplies wholesalers and then have a jeweler set the stones for you. Or you can commission an artisan to make settings for you. If you're starting from scratch, you'll need to find out the current spot price of gold (whatever karat you want). There are a few alternatives for obtaining the raw material. Again, you can get karat gold casting shot from a jewelry supply house (I used Swest for this 20 years ago -- don't know if they're still in business). You could also look at the scrap gold listings on eBay -- the price of this kind of scrap rarely goes above melt price (more or less the wholesale rate, so to speak). If you do that, pay close attention to the weights and karats listed. Each karat value will be calculated differently as to the percentage of gold involved. (I used to have a spreadsheet I could use to do the calculations but who knows what happened to it.)
Finally, gold is sold among professionals by the penny-weight (abbreviated "dwt"). It would be a good move to find an equivalent table if buying from a seller here listing the merchandise by gram. Most auctions here do not go by penny-weight.
Sorry to be so long-winded! Opals are a true love of mine and setting them for use makes my heart sing. Keep us posted on what you plan to do!
