A couple of things - overall, I think it`s good, and it might just be me, but when I first read it I assumed the GC branded your food, rather than something that stays in the food. Does that make sense? I think that right at the top of the page you should have a photo of the GC in action. Is it just me or do you have a picture of a cooked steak with no GC? Definitely I would show the product in use first thing.
And I agree with whoever said it might not be the best idea to compare your product to wine charms - I know what they are, but they`re not the most common household item, so I wouldn`t recommend having your reader`s mind immediately going to something they might have to stop and think about (or google). Basically GC are a "name tag" for your food - probably you can think of a better way to put it, but that`s more descriptive to me and as a reader I don`t have to think one second about what that is or how it applies in this context.
Lastly, I would recommend making GC that say "rare," "medium," "well-done," etc. You can even have a more colloquial version that say "bloody," "scorched," etc. Or maybe that sounds too gruesome! I do think it would be helpful, so the diner doesn`t necessarily have to remember which charm they selected, and if you were in a large party situation where it might not be conducive to have people select a charm, but they`d still want to know how something is cooked before they eat it.
Hope that`s coherent! Best of luck to you!