Caulk for rebuilt mantle

[2PistolPacker]

My daughter started a Pinterest fireplace project about 18 months ago and I told my wife shortly after that I will inherit this project some day. Well about 2 months ago she called and let me know she was in over her head with this project and if I would "come look at it". Well it's almost done now and only two things left, caulk the seams and a final coat of paint. I don't want to use the same Rutland caulk I used to tuck the firebrick as it has too much aggregate in it. I thought of using a sanded caulk like I used around the tile in my bathroom remodel, but am afraid if anyone uses the fireplace it would melt or worse. Are there any high temp products around to fix this problem for me. The area is the gap between the new stone tile and the black steel fireplace front. Thanks

 

[DAKSY]

Black RTV.

(broken link removed to https://www.rutland.com/p/3/500-degree-f-rtv-high-heat-silicone-sealant)

 

[2PistolPacker]

Black RTV.

(broken link removed to https://www.rutland.com/p/3/500-degree-f-rtv-high-heat-silicone-sealant)

I have seen this product and will use it if I can't find something that matches the stone rather than the fireplce front, thanks, DAKSY