How do I know if he has rings in it??
You can blow straight down in to it, or pull a swath of fur forward with your hand. You should see layers of different color showing from the base of the hair to the tip. Agouti coats, including chinchilla, have 3-5 different rings, sometimes up to seven.
Here is a photo of chinchilla ring color from the Giant Chinchilla Rabbit Association's website page
Evaluating Your GC
You can see the slate gray undercolor (next to the skin), the pearly middle ring, a black ring, another pearl/white ring, and the black tipping. The rings could be a little better-defined, but this is a good example of ring color.
An absolutely fantastic image of crisp ring color is the lynx mini rex coat pictured below, with white undercolor, fawn inner band and lilac tipping. This is one of my favorite ring color photos *ever.* It's from Wildriver Rabbitry's Mini Rex Color Guide
Mini Rex Color Guide
Incidentally, the best way I've found to tell what base color an agouti is, is to look at the color of the lacing at the edges of the ears. That way a less-than-ideal coat, e.g. too light ticking in a chin or a wideband gene increasing the rufus factor in a chestnut, can't confuse you. Your bunny has black lacing, hence a black chinchilla (assuming he's got bands, even if they're indistinct).