Hi to all who read this, and thank you in advance for any suggestions. I purchased a distressed house and the former owner/builder did not complete the fireplace. It is gas, which is hooked up and functional but the fake stone was not grouted between the stones and part of the stones have been varnished. One mason told us the varnished stones need to be removed and replaced, then grout the rest of the stones? To me the unvarnished stones look pale and unfinished. Is that the way they are supposed to look?
Thanks for reading.
The firebox itself (the sides and bottom of the firebox and the smoke chamber area) must be done with refractory firebrick and refractory mortar. Regular stone and mortar will not only allow the passage of extreme heat into the masonry and the adjacent framing, it will also fail. Your joints in the firebox cannot exceed 1/4". A brick/masonry supplier can provide the appropriate materials. If you currently have stone, take it out.
As for the stone on the fireplace surround, the sky's the limit. As long as it is noncombustible, do what suits you. As a good rule (and per code), wood should be kept at least 12" from the fireplace opening in every direction. The code is much more complicated than that, but with at least 12" you're safe 100% of the time.
If we're talking about a factory-made gas appliance fireplace, that's a whole different animal. If it is gas logs installed in a masonry fireplace, stick with the first thing I said.
The colors of the stone can be deepened with a stone sealer/enhancer. There are various ones on the market. Try it on some scrap pieces first to decide if you like the look. Also try it separately on the grout, just in case there's a change in color you don't like. If it's okay, then seal the stones and grout at the same time.