How old is your cat? Have you given it a bath? Sometimes as cats grow older the hair color will change slightly, depending on the breed or the mix of breed.
I live a Blue Russian/Siam mix. He is getting older and the Siam colors are starting to show (he really took after his papa and not his mama) where his hair used to be a very light grey.
Bathing your cat may help. Cats do need to be bathed, even though most ppl think that just because they 'lick themselves' they are able to keep clean. This is not the case. Remember, the cats we live with are 'domesticated' cats. That means they depend on us for certian things..the minimum...food and water. But they also require more.
Bathing should be a routine. Yes, they fight at first, but they get used to it and feel much better for it. It clears the dander that builds up that they don't generally get rid of because they don't brush up against trees or bushes whe the intensity as wild cats would. Not doing that also leaves dirt buildup on their skin.
And with the dander, if they should get a scratch, this dander and dirt can spell an infection, but you probably wouldn't know it because they will hide it if they are sick, until they are really really sick.
I bathe the cats I live with at least every 3 months. Where I 'work', at most 5 days after they are admitted, if they are ready for general population.
Interestingly...all Siamese cats do tend to darken with age across their whole body. I have seen it happen with every single one of mine (granted, that number is only 4, but still....). That's why these guys tend to have short show careers and then only as youngsters.
Mink is a color that is normally reserved for describing Tonkinese cats, which are another one of my favorites.
Color descriptions in cats can be pretty difficult especially because it seems as if most of the major cat organizations have different names for the colors and even, sometimes, different classifcations for the cats. For example, a red point Siamese is shown in the Cat Fancier's Association as a red Colorpoint Shorthair, but in England, with the GFCC, the cat would be considered a Siamese. Himalayans are shown as Persians here in the states, but have their own classification in Europe. It can be very confusing!!!
Sorry for the thread hijack...but when it comes to talking about colors for cats and cat genetics...I just can't help myself!!
When I had my red point Siamese mix, I noticed that as she got older, her coat on her back developed a darker creamy red color that was almost golden. It was a pretty color actually. I think I had asked the same question about the color of her coat, too. I believe I was told the same thing about her coat changing color as she aged. My cat book mentioned another color called mink, so I remember asking the vet if my cat was really a red point or a mink point. He seemed to think that red point was still the correct name of her coloring. Either way, she was still the same pet cat that I had grown to love dearly. She would never have made it as a show cat, since she was simply too painfully shy for such a thing.
I had a short hair cat who was called Slate since he was a slate grey color. As he got older if you saw him in a certain light he would actually look brown around his sides and back area. I thought at first it was because he was probably outside rolling around in the dirt. But I tried brushing the "dirt" off and that wasn't it. I never knew why but just chalked it up to his getting older and since he was already "grey" he turned brown instead.. LOL.