Placing Gems

@MagicalArtemis Transfiguration is an activity (not really a skill) that came with WA. You need to buy the Carter XL Display case, which is in sort by room/storage/displays, and then place eight objects on it. The process costs §500, and what you get in return can be a bit complicated. But the highlights are:

• You can use cut gems, smelted metals, and certain other items like relics. But seeds are ineligible, as are magic gnomes (I've tried).
  
• If you place only gems, and at least five different kinds, you get a soulpeace gem, worth (so far for me) §3,750 ±500. It can be cut the same way other gems are.
  
• If you place only gems, and at least five different cuts, you get a skull cut of one of the gems. I've read that using at least five of one particular gem (though in different cuts) will guarantee that the skull cut is of that gem. Otherwise, your chance of getting each gem depends on how many of each you used in the process.
  
• The value of the skull cut seems to depend only on the gem it's made of, not the value of the gems used to make it.
  
• If you place metals, you can create larger ingots of the same metal, compendium, or supernovium, depending on what you use. I haven't done this yet, so I don't have much insight.
  
• If you mix gems and metals, or add in another object like a relic, the result depends on how much the initial materials cost. You could get any number of items, but if the cost is between §3,500 and (I think) §5,000, you get a cut Tiberium. It will grow to a large spire cut, worth maybe §35,000-§45,000, in a day or two.
  

Carl's Sims 3 guide has a more comprehensive walkthrough:
https://www.carls-sims-3-guide.com/skills/collecting/worldadventures/transfiguration.php