Yes, the first successful laser, created in 1960 by Theodore Maiman used a ruby. They are still used in some lasers today.
jewelry
The prices for precious gems is dependent on supply and demand - not on any particular physical property. If people prize a certain gem above another then they will pay more for it.Consider diamonds and Rubys. Diamonds are harder than rubys, in fact they are the hardest mineral know - yet Rubys are considered more valuable.
no such thing as rubys in minecraft
Platinum jewelry is more resistant to scratching or denting, but it does not necessarily last any longer
In most cases the answer is yes, simply because of the fact that fine jewelry contains many more rare gems than costume jewelry does, which is most often made of plastic or other synthetic materials.
glassy
Yes, David Yerman jewelry is more expensive than most brands but he carries a very good jewelry line. The prices for earrings on his internet listings are quite expensive.
Personalized jewelry typically costs much more then regular market jewelry if you are personalizing things such as settings or stones. Engraving is a cheap way to personalize jewelry without breaking the bank.
Red
red
Rubys
Pure gold is too soft to be used in jewelry.