These seem to be my options?

Normally I'd say marble pencil trim or something similar for such a classic tile, but since you've got the black fireplace insert in there, the Schluter will look just fine, too. (It'll disappear, which is the best thing a Schluter strip can do!)

So...whatever is easiest to install I guess? You have 2 good options!

Dude, pencil. Make it disappear into the surrounding field tile -- Schluter is only for slick ultramod bathrooms with a complete contemporary envelope. Not knowing how you'll furnish this space, you have classic windowsill and base molding that aren't ultramod, so don't fight them and keep it consistent.

Does that look like what they did in these two photos? Just polished, grouted, and caulked on the inside edges closest to the insert? Thanks for all the advice!

Here is the unfinished, adjoining kitchen for perspective.

I can't enlarge those pics enough to see, but it appears so. you can't put wood next to the firebox, so i'm guessing they've polished the edges. all you need is some sandpaper from 220 up to 800 or so. I've done it. marble is very soft and you can put a honed finish on it pretty easily. if you want it shiny polished, you'll have to graduate up to higher grits. I'd stick w/a honed finish,,,no one will see it.

You could also do chair rail molding for the outside if you didn't want to do wood. or the marble pencil liner that lays flat would be another option.

I like your kitchen. are you doing the same tile as your backsplash? I'd do something w/some black for more contrast. maybe cement tiles,

or the darker marble w/the nero marquino. like the chevron tile in my niche. that would good as your splash.

this splash in a herringbone would look so cool..I'd take it all the way up to the ceiling in your kitchen, and above cabinets.

Thanks, Beth! Do you polish before or after the tile goes up? Sorry, I'm so clueless about all of this!

A matte black "L" profile will match the gas stove insert for the cleanest finish. Often the insert is recessed or uneven to the wallboard face. Here I used two pieces back to back. 1 goes inward to cover the unevenness and 1 outward flush with the tile/stone. I should have taken the photo after cleaning:)

incarrozza,,,it's much easier to do it before. remember, if you do go that route, all of your edge cuts are going to have to perfectly straight and even since you won't have anything 'hiding' them. Creative Tile posted a nice suggestion w/the metal trim piece. you can find one w/a low profile. go to a tile place that sells them and they'll show you. they can show you how to polish the edges as well.