Struggling with diamond render

[ElizeV]

Hi all,
I'm trying to get a realistic looking diamond ( the image is just showing the gems) for a catalogue image - so kinda has to be white colour background and front view angle. I tried many different HDRI setups, thin tube physical lights, reflectors and 'studio' lights nothing seems to work. It still looks like  I painted it in Illustrator.
The main stone is my biggest worry, smalls look OK in other renders. I'd love to get it brighter, with more light areas, but still maintaining good contrast and some colour, but as soon as I add more light it washes out and goes all low contrast and 'grayey'


Stone is fairly standard diamond / gem , Abbe number 30 for colour
Ray bounces 32
Sampling 16
Global illumination on
Caustics are off - I found they add too much noise on the ground for these shots
Product mode

I am using Keyshot 7.3 Pro

[DMerz III]

I can't remember, does Keyshot 7 have Photographic mode in image styles? That would go a long way in giving you more tone mapping control. The basic image style is prone to hot blowouts like this.

If you don't have photographic mode, you could render in 32 or 16-bit output and tweak the exposure/gamma values in post (photoshop).

You might even be able to get away with gamma tweaks in Keyshot, but again, can't remember how effective that was pre-photographic mode.

[ElizeV]

There is no photographic mode in 7, but gamma adjustments improved it a bit, thanks!