Your Questions:
What color mutations can be involved in shows? When do you stop showing a chinchilla?
The color's of animals at the shows are the following:
White, Sapphire, Violet, Beige, Standard (Naturalle) Ebony, Black Velvet. They have been putting Blue Diamonds in with Sapphires at the shows I have been too.
It's a bit difficult for me to break it down even further with the MCBA classification prior to the show as I don't breed white. The judge and animal handlers will break the animals into the same colors and phases. They also break them down into age groups and sex. They do not mix the sex's of the animals. It will be all young males, all young females, older males and older females.
When separating the color phases for the MCBA, they will move them into groups of light, medium, medium dark, dark, extra dark. And the white will be classified and separated into groups as well. Sorry I don't know all the white classifications. And I know I am going to miss something here. Just giving you a vague reference. Only the judge and animal handlers are present. The audience and breeders are not in that area. After the animals are classified, the show begins.
You can show animals at any age. I think most would agree the first year or so is the best time to show. Longer than that, the blacks and beige tend to turn a bit rusty looking on the tips of the fur. That isn't good for showing. It is called oxidation. And we all wish our animals are in prime when showing. That is when the fur is at its best.
Pets can enter the show as well. Breeders and ranchers will spend several months preparing their animals for the show. A pet may or may not have anything done to them before the show. I try to talk to the pet people at shows. They have many questions. While some may never breed or show again. I'd like to think I have the opportunity to inspire someone to be a future chinchilla breeder. Perhaps that person will feel more comfortable and find a mentor.
You can find some really nice photos down in the "Show" postings. Tiffany took some nice ones at the SEC show this year and put up a link. Most people will post several photos after the show is complete. The shows are so spread out across the nation. I know making it to California isn't possible for me. But I like to see the photos and look at what people are working with.