Hooobi,
Rubies and sapphires are chemically the same except for trace elements that give them their color. They are both corrundum. There was nothing special about the particular site I listed, other than it showed up on a web search. I double checked, and they do list ruby red corrundum. If you do a simple search for synthetic ruby, you will find lots of places on line that will sell you cheap cut stones either loose or mounted.
If you want the good stuff ($200-$600 per carat), then try
www.ramaura.com or
www.chatham.com. They have to put special trace elements in the good ones so they will flouresce under special light, otherwise even jewelers with microscopes can't tell them from natural stones. I have purchased a few good quality stones and even the lower grades are night and day better than the crap you get in cheap jewelry from the mall shops. Chatham is even trying to sell synthetic diamonds commercially now. Chemically identical gem quality diamonds, only man-made. For some strange reason my wife almost killed me when I mentioned synthetic diamonds for a wedding ring, but she absolutely loves her synthetic ruby earrings.
SinMen,
I think if you check your expensive old watches, you will find rubies. Many of the bearings are cylindrical, and it is extremely difficult and completely impractical to make one out of diamond. You would be drilling diamond with diamond, and you don't get anywhere very fast. You might find a few watches with decorative endstones made of diamond, but the majority of the expensive movements will be ruby, sapphire or garnet. BTW, corrundum is alumimun oxide, so alumina is probably a brand name of synthetic ruby.
I've learned way too much about this crap going through a wedding and a few anniversaries. Personally, I think getting the wife or gf a pair of ruby stud earrings for $400 that would cost $3000-$5000 if they were natural is a hot deal!