I couldn't believe my eyes too, after seeing my first test render. LuxCore's shaders, even in their default settings, can really make ordinary stuff look awesome.
And these are just amateur-level renderings. The stuff I see in a certain YT channel of a real jeweler-turned-3D artist makes mine look like crap.
Oh, and your card's glitches are probably just a driver issue, or maybe something that a Windows update can fix.
I haven't done the shiny gemstones yet (just gold and some non-transluscent quartz type rocks), I imagine they'd be pretty hard to get looking right.
I use Linux, several updates hasn't fixed the issue (but probably are at least somewhat affecting it as it's better or worse after some updates XD), may also be hardware related. One day I'll have enough money to take it back to the shop for upgrades.
I love Linux, especially how its graphics subsystem has such low overhead that rendering is faster in it, and basically any graphical operation too.
Back in 2007 I installed a DVD of opensuse and instantly fell in love with it, that I uninstalled Windows XP. I used it until 2010 and reverted to Windows because of some software needs.
And last year I was using Puppy Linux alongside Windows 10 if I needed to do some heavy modeling and not need my graphics tablet, since it does not work in Linux. So I switch back and forth with it and Windows just to be able to sculpt and run other stuff.
Not a Wacom tablet? That's what I've got, everything works fine. Well aside from the gui utility thingi, I don't know what it's like now but at the time I looked at it several years ago it left a LOT to be desired so I ended up having to write a bunch of scripts for my apps to set the pen and tablet buttons and triggered by gestures drawn with the tablet XD Haven't tried looking at the gui since though as the scripts are still doing their job to this day.