It's hard to tell without pictures. Can you post some pictures? You can custom color the veneer to match the existing stone. Or you can choose a stone that has more of a traditional feel.

https://www.etsy.com/in-en/shop/Bleucoin?ref=hdr_shop_menu

A Rumford design is very shallow, has outward-flaring sides, a back that arches forward, a curve on the underside of the front lintel leading back to a broad slot-like flue with a flue chamber above it. The overall front opening is almost square, sometimes slightly taller than wide. Rumford fireplaces are very distinctive looking. You can get some basic information from this wikipedia article here: https://en.wikipedia.org/wiki/Rumford_fireplace and there is plenty of info online, even ready-made reproductions (more or less accurate). Rumford developed his improvements and published them in the late 1790s, just before fireplace heating was displaced by stove heating (a process already well underway when Rumford developed his improvements). Good luck with your whatever you decide to do.

Hi all, bought our first home and found out mid sale that fireplace has to be fully replaced. getting it replaced and want to go from first pic to second pic for my fireplace - fireplace is gas, material around is rough drywall. Any ideas please? I just want a simple finish with a floating wood mantel. do I have to use wall boards? help!