Which gems can be prepared on a small scale basis? I am interested to know the following:


Which gems can be prepared at home (without sophisticated instruments)?
What will be the quality (appearance) of the product for a certain method?


I want these information just for hobby-scale purposes(no academic/commercial production). In addition to common lab equipment, I have $\pu{1000 K}$ of temperature and few atmospheres of pressure at disposal.
Most likely the only gems you will be able to make at home are plastic gems.
Wikipedia sheds some light on the production of some synthetic gems, Corundum and Cubic Zirconia, both of them not possible at home (or at least my home).