Framed painting on stone slab

My husband was given this art (and other pieces) by his youngest brother before he passed away in 1989. Frame is badly damaged. It's heavy, just over 9 pounds, measures 32 1/2" tall x 24 1/2" wide x 3/4" deep including frame. Visible portion is 22 1/2 tall x 15/78" wide. I'm really not sure of the medium. Sometimes I think oil, some parts remind me of water color. And I could be wrong on both. haha. Matting is silk. Also, I don't know what the stone slab is. Kind of reminds me of marble, but then again there's about three more stones/minerals that vaguely resemble this slab. Of all the paintings, prints and etc. that I've looked at trying to figure out which Asian likeness this painting may be representing, well, I've never seen any clothing that has the upturned, winged collars other than Mongolian examples, which are far and few between. I also wonder whether it's Chinese, Japanese, Korean or somewhere completely different.
The colors (like the blue and gold) depicted in the garments can represent royalty, such as the brocade details, knotted art belt with tassels (but doesn't appear to have a pendant or other heavy object attached to it). It could also represent courtesans, actors/dancers, and "beauties". Maybe even a likeness or depiction of Songiin's mother from "Nine Cloud Dream". You can tell I'm really reaching here. lol. But the garment in total is elegant, has the elongated sleeves, the knotted art belt (which almost rules out Japan, as Japanese "obi"'s are usually much wider), the brocade, the tassel, etc. It almost looks ceremonial. I learned that geometric patterns were reserved for male clothing, plus men wore their hair in buns, but this hair is much more than a bun in my humble opinion. I took this piece out of my husband's semitrailer where it had been stored until we married and cleaned it and hung it on the wall, out of sunlight, to try and protect as much as I can without getting it restored, but I'm dying to open the back and really look good at the art. It would be nice to at least have the cardboard removed and replaced with acid-free material, and the glass changed out to protect it from further decay. It looks like it got wet at some point, which you can see in the silk matting. It'd be nice to have the frame restored as well. It's a beautiful art piece either way, to me. If anyone can shed any light on this, I'd appreciate it. Thanks for looking!

**I am SOOO sorry for the sideways pictures!! Again!! Aaargh. I tried turning the photos 270 degrees, thinking that if it automatically turns these photos 90 degrees counterclockwise, that turning and saving copies in the 270 degree copy that when it posted to CW it would turn it the rest of the 90 degrees. Didn't work. Will do my utmost to research and try other ways to get the photo to post right way up. I took the pics from my phone, but am uploading the pics from my laptop. Thanks for your patience. This is the second item post I've had to deal with this, and I know it's frustrating to you as well. Sorry.