Since I've started writing this Swearingen post, there have been 4 replies.
Part of living in this society is to blame I think. but oh well - Nope, jealousy has been around as long as mankind. The lesser animals probably have a simpler emotion, we just haven't recognized it.
What to do?
If it's causing you physical signs (tense body, raised heart rate, etc.) try to leave the situation and maybe just some fast walking to take care of the extra energy jealousy involves.
Acknowledge your jealousy, but tell yourself that no one can have everything they want or need. I often tell the PR that Even Bill Gates and Steven Spielberg can't have everything they want and they're immensely wealthy. They can't buy a cure for an incurable disease.
Take a hard look at the thing you're jealous over. What are the pitfalls of having it? What will you have to sacrifice to own it? Cars and houses are expensive to own and keep up. If it's a person just know that not every relationship goes smoothly, PA has to put up with me and I have to put up with him.
Besides, you don't know what the person has had to sacrifice or prioritize to get the thing. Yeah, they may own a nice car, boat and house, but they may be a half a step ahead of the collection agency.
Figure out what gives you pleasure in life (and we know what that is, your rocks) and focus on that. As Suze Ormond says, People first, money second, things last. In other words, have healthy relationships with people, mind your money for your future and indulge in pleasures when the first 2 things have been taken care of.