One problem a lot of people are having is that fabricators and installers are using an epoxy for the seams in white marble, quartzite and even porous quartzite counter tops.
The problem is that the resin is bleeding into the white and porous stone and thus causing a yellow or grey lines. David gets calls on this every week.
The answer is that they are using a less expensive adhesive that is yellow or not UV rated at the start. Urethane adhesives are the only one that does not bleed or yellow over time. Glacier or Last Patch Diamond by Bonstone/Touchstone is one of the best counter top setting adhesives in the industry that does not yellow or turn grey on the seams of your white marble or porous stone counter tops. Please follow the link for example.
The other thing is that the glue they use is not going to hold up in the sun or outdoors and the lams or laminations can come loose and fail.
Please follow the link for example.
Example
David Bonasera worked with Keith Graves on the ( MIA) Marble intuit of Americas Design manual a few years ago and once finished, it was sent to every glue manufacturer in the stone industry in the world and approved and blessed by them. Now this is the standard for glues and adhesives.
(PLEASE CHECK WITH YOUR GENERAL CONTACTOR AND FABRACATOR TO MAKE SURE THAT THEY ARE USING THE RIGHT ADHEASIVE FOR YOUR COUNTR TOPS) Don't let them BS you. Urethane adhesives are the real thing. please down load this and print it out for current or future remodels.
MIA Adhesives chart 
