Hi Michelle!
I just started with Jewel Craft so I might not be able to answer all of your questions, but I've found some nice hints during the game.
There's an icon below the gem that needs to be manufactured. It looks like an open book. When you move the mouse cursor over it you see a list of "items to gather". This helps a lot. It doesn't show you how many stones you need for a particular jewel, but you'll learn that during the game.
The most important bonus when it comes to combining a large number of stones is the hour glass. It allows you to turn five stones without causing a "chain reaction". Last level I had to create a giant rubin made of 12 red stones. I turned as many red stones as possible (always in pairs of two leaving one stone free between them) and then activated the hour glass and turned the vacant stones.
Make sure that you create the largest items first, because otherwise you're running out of available stones in the end.
Kind regards,
Maui