Can confirm, found only a ruby in that location.
I just went to this location, and I found a flawless ruby on the opposite side of the throne from the regular ruby. I almost passed it up as it looked like blood.
Grab a torch! I looked for a while, found them on the right-hand side by the throne. Skyrim Special Edition patch 1.2. Confirmed while you walk, the Flawless ruby does not scatter. These gems will stay in place when walked on. Blends with blood! Happy Hunting !
It is there by the empty fire pit
Uh it IS in South Shriekwood, like others have been saying you just aren't looking hard enough so let me spell it out for ya:
1. Sit on the throne, so you're facing the torture tables
2. Go left and stop at the empty fire pit next to the throne, if you're facing the throne then it's the fire pit on the right (The opposite fire pit on the other side of the throne is lit)
3. Right in between the staircase towards the throne and the unlit fire pit in a small space is the Flawless Ruby
If you're still not getting those instructions then I can't help you
There is a gem in the location that you're talking about, but it is NOT always a flawless ruby. Sometimes it is just a regular ruby. Admittedly, it's pretty rare for it to be a regular and not a flawless, but it is not guaranteed to be a flawless ruby.
You can confirm this by loading it up in the creation kit. You know, that is if you can stop being a condescending know-it-all long enough.
There a lot of people saying there are only rubies here, not a flawless ruby. The actual truth is there are 2 rubies and 1 flawless ruby in the same room. Bethesda just did such a damn good job blending them in with the blood and hiding them underneath stuff. Look under all of the pots in the room. I found the two rubies on the ground in the blood and the flawless ruby under a pot to the left of the throne as you would be sitting on it. Use Candlelight or Magelight (i used both lol).