Fwiw, I just mixed faux-marble quartz (Lagoon) with a Carrera backsplash and at least in it's pre-grouted state, I'm really happy. It was hard for me to find a backsplash that worked well with the grey-ish tones of the Lagoon, mostly because my cabinets are painted taupe. Anything that "matched" the cabinets seemed too brownish for the counters. The Carrera blends the two perfectly. I think it also works because I wound up using a very small-scale herringbone pattern, so the patterns in the marble tiles are less pronounced. Fwiw, I don't see the calacutta tiles that the OP posted working with a greyish quartz that's similar to Lagoon, and I'd also be concerned about pattern overload with a subway tile. But having worried about the fake-next-to-real problem, I wanted to at least add my experience that it can be done. One of the prettiest kitchens on here, done by a pro, is GW user @kompy, who used a different marble subway with Lagoon counters, and it looks stunning.

I'm not sure one has to limit to 2 or 3, but keeping, say, faucets the same, knobs the same, etc, is a good rule of thumb. as for how many metals to mix-I'd say depends on the space, and how much it can be repeated..not neccessarily in metal itself, but with color of other material reminiscent of metal I mixed the metals the most in master bath. I have there: polished nickel faucets and fixtures; antique brass drawer pulls and cabinet knobs; copper canopies and details on glass pendants that hang on black cords; and ORB door hardware. It sounds like a mess and I was deadly afraid when deciding to go for it; yet it looks pretty seamless, because: -polished nickel plays well with the wall tile and countertop marble(main color very warm gray) -ORB hardware repeats somewhat black pendant cords in its color -since marble has rusty golden streaks in it, copper in pendants canopies picks it up -the vanity is teak(lighter warmer brown) and the tile is shaped terracotta(darker warmer brown)..antique brass pulls I used on the vanity blend in with the vanity itself, and their shape repeats terracota shape. Nobody knows how much courage I put into this mater bath lol; I'm not even sure they see how different finishes are; they just see a space they like a lot. Repetition does wonders for harmony. you most definitely can mix ORB with either brushed nickel or polished nickel what I wouldn't do-I woudn't put polished nichel and brushed nickel together for example. Or i wouldn't pair nickel and chrome. They should be different enough to mix them properly. Oh, and of course I'm not a designer either. Just sharing my experience from a recent very long and big remodel. Of course one becomes braver after one tries something. I never liked to match anything; and now inclined even less so:)

The first two lights we ordered in brushed nickel, and those are the ones backordered. The last one we already received and my husband already installed bc he’s antsy, so can’t really return....we want something like the first two but can’t seem to find it in nickel. I’ve found similar items in matte black and antique leaf silver. Were in the process of redoing our kitchen, so we are changing everything out from ORB to brushed or satin nickel

Just to add, the kitchen appliances will be stainless steel gourmet, with a 48" range. I've decided on chrome for the plumbing fixtures since it is less expensive then the other finishes (and we need to reduce costs where ever we can since prices have gone up in just a year's time). I can change the kitchen faucet to a "spot resist stainless" finish (which is what I put in the last house we built, and the kitchen island lighting was 3 pendants in a brushed nickel finish, and that looked fine with the stainless steel appliances and black cabinet pulls). The only place I'm having the dilemma in finishes is the kitchen since the lights I like don't come in a chrome finish. The bathrooms will have chrome plumbing fixtures with vanity lights in chrome, and black cabinet pulls. Also, the door handles/pulls will be black as well. We are also selling this house, and it will most likely be a second home for the buyers.