Updated: Dec 30, 2021
Here's something you might not have known: Sapphires come in every color of the rainbow, and when they are red, they're rubies.
If you use the term sapphire alone, that denotes blue. The other colors are considered fancy sapphires. They come in everything from colorless or white to green, yellow, purple, orange, pink, and even some fun combinations like bluish-green or teal, or purplish-pink or orchid.
Sapphires and rubies are good choices for jewelry as they have a hardness of 9, take a great polish, and withstand wear and tear very well. Natural sapphires and rubies are almost always heated to enhance their color. Still, some incredible colors occur naturally without any enhancement-- if you're looking to buy a piece like that, ensure you ask for documentation and be prepared to spend quite a bit.
Sapphires and rubies were some of the first gemstones ever synthesized in a laboratory way back in 1873, so be on the lookout for lab-created gems, even in antique jewelry. In fact, synthetic sapphire was often used in the Art Deco pieces of the 1920s and 1930s because it was believed the consistency of color and lack of inclusions in the lab-created stones was an improvement on natural.
In short, sapphires and rubies (mineral name, corundum) are wonderful gemstones, incredibly wearable, and suitable for just about any piece of jewelry you can imagine. I have really only scratched the surface of information here, but as always, feel free to ask any questions you may have!