Try some Tenax Pro Seal in an inconspicuous area such as an appliance edge. If you like it, do the rest.

Do the water test -- put a small amount of water on the stone, it if beads up and doesn't absorb, the stone doesn't need sealing. Not all stone does. Or you can take a scrap piece and do the same thing with oil, ketchup, soy sauce, etc and see if any of it stains or absorbs.

Over-sealing is bad, too -- happened to me and ended up with a cloudy finish, had to strip it with acetone.

I hadn't heard of Black Infinity so I looked it up. I highly doubt that it's quartzite. I can't really tell what it is by looking at photos. Have you been able to test a sample?

I would go with what the fabricator says.

I haven’t been able to test it because the slabs are at the fabricators shop. He says he will use 314p impregnating sealer from granquartz. Are these types of products ok for the kitchen, or should it specify that?

Hi everyone, thought I’d share an update in case anyone is interested. I did a water test and 30 mins later nothing appeared to have absorbed. I wiped it away and there was a slightly damp/dark spot that disappeared quickly. The stone looks beautiful and natural, like a muted soap stone, so I’m glad I didn’t have it sealed. Very happy with it. Pics from install and water test 30 mins apart. Thanks again for your suggestions.

" I was assured that it’s quartzite..."

By a slab salesperson. lol. A meth addicted hooker under a streetlamp has more credibility.

It looks beautiful!