As far as I know, the gluten/gluten free status of SN products are not listed anywhere. I've always figured its more of a--read the ingredients and try at your own risk--sort of thing. Though if it is listed somewhere I'd love to know, as I'm gluten free too!
For what it's worth, I've been using SN products for several years, both pre and post diagnosis with no issues. My skin has never looked better! I just make sure to carefully read the ingredient listing for each product and if there's no listing, well, I don't use it!

The only skin reaction I have to gluten containing products is contact dermatitis, and that's only with sustained contact, so what's safe for me may not be safe for you... I've noticed that some of the moisturizers, face masks, serums, and skin treatments have oat extract and/or wheat germ oil, so I don't use those. I don't recall ever running into those ingredients in the eye shadows, foundation, or blush, but I still check the ingredients of each one before I order. I'm not a huge lippie person, but those that I do have don't list any gluten ingredients and I've never reacted to them.
Hopefully someone more knowledgeable will come along and post soon (I think they're all busy with the Valentine's day release, site revamp, and moving to a new shop!), but until then, I hope what I've posted helps some

Gaining certification for gluten free products is a costly process as far as I know, so most companies, especially small ones, don't even attempt it. But there certainly is a need for safe, high quality products in the growing gluten free community. I still haven't found a shampoo & conditioner that's all natural, gluten free, and actually nice to my hair!