Almost all rubies on today’s market have been heat treated for color enhancement.
Heated rubies are perfectly acceptable, but nowhere near the value of natural
Speak frankly with your jeweler about treatments.
Get all treatments clearly disclosed on your bill of sale.

Rubies have been color enhanced with heat, oil and dye for centuries. There is nothing unethical about these practices as long as there is full disclosure at the point of purchase. Here's a few hot tips about heated stones.

1. The great thing about heat treatment is that it permanently enhances the color of rubies, allowing many more high quality rubies to come to market, keeping prices reasonable.
2. Almost all rubies on today's market have been heat treated. Unless you are a serious collector only interested in top quality natural stones, assume any stone has been warmed over. But, unless you're shopping at Harry Winston, if your jeweler insists that his stones are all natural, tell him "that's great, but I really wanted a heat treated stone." His rocks will get hot so fast, they'll sear the diamonds in the next case.
3. When comparing rubies over a carat, remember that natural stones can demand up to 40% more than their warm cousins.
4. Natural stones of quality should come with documentation to that effect. If your jeweler insists that a stone is of natural color, ask for the lab report. If he doesn't have one, get one done. Whatever you do, don't pay natural prices for treated stones.
5. You can always take your ruby to a professional gemologist, he can almost always tell if a stone has been heat treated. The trouble is, he can't always tell if a stone hasn't been. The point is, they offer an impartial analysis of your ruby, and that in itself is worth a fortune in peace of mind.
6. Oh, yeah, don't try to heat treat your own stones. That is, unless your microwave cooks at 3,000 Fahrenheit. Even then, you probably would only destroy your ruby, but you could cook a potroast in about a half a second.

Oiling and dyeing is reserved for lower quality stones and is not a permanent enhancement. Again, this is not deceptive unless you are told that no such treatment has been done.

Surface cracks are necessary for oil to penetrate the exterior of the stone. If you come across a suspicious specimen, ask the jeweler to run it through his ultrasonic cleaner. If your assumption was correct, the stone will probably come out a little lighter and the cracks will be more evident. If the jeweler tells you the stone is too delicate for the ultrasonic, ask him why he's selling it.

A relatively new treatment is surface diffusion, the good news is it's permanent color enhancement, the bad news is the new color is only skin deep so you will have a beautiful stone, but if you scrape it, the gray roots will show. Gemologists can fairly easily detect the treatment, but, if you're just looking at a petite pendant, save your money and get some matching earrings.

There are many high quality treated rubies on the market and you can own them with pride and confidence.The trouble with treatments is not that they are done, the trouble is that most people don't want to hear about it, which means jewelers aren't inclined to talk about it. But if you are spending several thousand dollars on a ruby, do yourself a big favor and get all treatments clearly disclosed on your bill of sale. Treated stones can require special care. Better to lose the illusion, than lose your money.

Answer to quiz: c