How can I get a tinted highlight without tinting the entire piece? I want to give my highlights a little more color, such as in this image:



But using an environment map gives me pretty flat colors:



Is there a way to get this greater hue range, especially if I can get it just on a single object? 

I tried adding a second light, but it really doesn't look good with environment lighting.

I also tried it without the environment, but any colored light tints everything that color, which I don't want. I want the shadows to be unaffected.

Compositor is fine too.

Edit this works, but the screen step seems too yellow:
First you can check Color Management, by default its set to Filmic that has a flat look (but for a good reason). You can switch to Standard, but probably better is to add a few nodes in Compositor - like Glare node.



Yeah ... separate effect for gem you can use ID mask of object or newly Cryptomatte feature.