Oh! Oh! I think I got this, let me try! I just did the granite thing recently.

Rock is rock. Slabs that seem to match are just from the same "lot" all mined together at the same time. When one lot is gone, the next can look very different. So having one slab from one lot and one from another results in two of the same granite types looking different. That's also why you can see a sample that doesn't match the current stock. With some varieties, I would see something I liked, and then the shop would say their current stock has recently been coming in more beige than white, or similar. Depends on the location in the quarry and which quarry.

Slab come in 2 cm and 3 cm thickness. If I remember correctly, 3 cm is more popular on the east coast and 2 cm on the west coast, but either is fine. A 3 cm slab can have a slightly larger overhang before needing extra bracing.

The finish could be as simple as dust in the slab. One place I went had a bucket and squeegee on hand to clean off any slab they pulled out for me since the slabs were in the same pen warehouse as the fabricating machines. I was surprised how much of a difference that made. I'm not entirely sure on this part, but I think they shine the stone up before install too.

The big difference is in fabrication skill. Search a little here for the install horror stories. You need to make sure they are good at templating, and if you have a seam, that you have seen their seam work. Also discuss seams ahead if you have a stone with a lot of movement. They should also be able to apply an even edge finish and consistent overhang.

OK experts, how'd I do? Did I learn it right? I hope so, I already made a deposit...

williamsem, I also researched this for about a year here before installing my granite last summer. Everything you said was accurate, to the best of my own informed-consumer knowledge!

Here's one stone quality trick: My granite installer had a guy that loved to talk stone. In my contract it said that when you get the edges cut and polished, the colors may not be quite the same as the top. I asked him why. He said that a number of slabs have some dye on that top layer injected in with the resin, and that won't obviously be on the side edge. He indicated they were slabs that come from China. I wasn't too happy to hear that dye was being put on granite. I mean, that was the beauty of it. It's all natural, right?
My own granite edges were consistent with the colors on the top, so I think I escaped the dye issue. I have attached an article on this point.

Also, if you do feel good about your stone yard, ask about who they like for installers. The guys who work there longterm know. I do think it matters that your installer's been around a while. Granite is a natural product; once in a while someone manages to scratch it or chip it, or stand on it to change a light bulb and crack it. The company who's been around a while will come and try to help you fix it.

A quality installer has computerized measuring machine to spec the dimensions of your walls and determine the cuts of granite for each counter. The quality installer will encourage you to view the finished plans to see how they plan to lay out your stone before cutting. The quality installer will do nearly all the cuts in the shop before coming to your home. They will NOT make those cuts on your lawn or in your home, raising large amounts of fine, gritty dust. Likely they have a large computerized cutting machine, as I recall it's a C&C machine. This cannot be used on certain style edges though.

Just please have your faucets ahead of time. Have the contractor measure the diameter of the inner water pipe and the outer housing. Some faucets give very little wiggle room. Be anal on this point; you won't be sorry.

Also, my granite installer was really picky on color matching the epoxy put in the cracks. It looks great.

HTH

Here is a link that might be useful: Dyed granite fades over time

Computerize cutting machine = CNC = Computerized Numerical Control

Mostly useless bit of trivia that only toolaholics care much about. :)

williamsem: thanks for the info. Your point about installation is well taken. I am working with a reputable kitchen design company that has a dedicated crew to do installation, including a granite fabricator. I've seen the work in their showroom (gorgeous!). Is that sufficient, or should I ask to see a granite install in a client's home?

colorfast: interesting article about the dye in granite. We are getting a black granite (Volga Blue). Should I test the slabs as directed in the article? Good tips about what to look for in installers; I'll ask our KD about how their fabricator works.

Still not sure about the different granite yards. The largest one in the area (60+ mile radius) has a large selection, though the slabs didn't seem to match well. Some of the sales people didn't seem terribly knowledgable. A yard that seemed more knowledgable, and had shops in several states, didn't have a great selection for us. The one that had the most beautiful granite (matched slabs, beautiful finish) had a sales person who wasn't terribly forthcoming for our questions (except to say that the granite was better quality because it was finished in Italy, but then he was Italian). How do you know whether it's a good yard? We are also relying on our KDs suggestions.

Will it make a difference in how the granite holds up in my kitchen?

Much of this is controlled by the variety of granite, the graining, the inclusions, etc. It it has lots of wild veins and non-granite inclusions, it's more likely to crack than a uniform granite with few inclusions.

Some of it is controlled by the skill of the quarry-master, the guy who decides which angle to take when following a vein. A good quarry will sacrifice some stone to get stable graining in the rest of the slab. Others are under instructions to maximize the number of blocks they cut, so they aren't as fussy.

Some of the really lovely stuff is so liable to crack that it's reinforced with mesh and resin in the quarry, and each slab they cut gets mesh and resin before they cut it from the block.

What I can't figure out is why there was such a price difference between slabs at different yards.

I've always been led to believe that there are differences in the quality from yard to yard, block to block-differing grades if you will (as opposed to price levels which vary by rarity)
This always made sense to me as it is a natural material- diamonds are not all the same, why should granite slabs be.

When we were getting our own, we were steered away from a particular lot to another one of the same material. Turns out they were selling the lot off to another yard, they did not want to sell it themselves due to quality issues- either lot would have been the same price to us at the yard we were at. I'd worked with this yard on many jobs and accoding to our fabricators rep (granite broker) they "carried only top grade stones- no junk"

Jakuvall - They may have been talking about the presence of micro-fractures and inclusions that would affect fabrication as well as "prettiness".

Selected, sequential slabs with striking grain will sell at a premium versus ordinary and random slabs.

lazygardens-Yes, they were talking about the integrity of the stone. I'm a KD so familiar with the differences in price levels.

My kitchen is small with no seams, and I didn't find ,much about any local places online. I didn't ask to see any local installs. If I had any seams I may have asked since there is some variation in my stone. I'm sure others here can chime in on this point. The showrooms always look nice, for a reason! Though I guess if the showroom doesn't look nice, RUN!

Check Angie's list and do some googling. The more complicated your kitchen is, the more likely you should try to see as much of their work as you can.

On showrooms: there's a Bedrosians near us with a small to medium amount of granite on hand. They also sell lots of tile, so the granite is just a part of their inventory. In their large showroom there are some bathroom cabinets with granite counters. Those counters are the reason we never seriously shopped there for our granite. The openings for the sinks were pretty haphazard: positive here, negative there, flush in some places. As williamsem said - RUN! We did buy tile there a couple of times, but we installed it ourselves.

Thank you everyone for sharing what you know. I am still learning.