Repairing marble kitchen counter top

[akoroma]

Attached is the sketch of an 8ft marble top that I am in the process of repairing. The top has a cut out for kitchen sink as well as stove top. While removing from an older cabinet, it cracked and came appart on both ends of the tappered section of the stove. Please see the marked red lines of the diagram! I now want to re-install but I am wondering if I should glue the two together first and later install the whole piece on new cabinet or should I lay it on cabinet then glue both together at once. Please advice for best type of glue to seem the two together as well as glueing the marble on counter.

 
Thanks!

[Mark D.]

First of all this is not a seam, this is a repair. I would epoxy the pieces back together flush before reinstalling it as the cabinet underneath may not be level and this may prohibit you from making it flush. Remember that when you reinstall this piece the stone will be very weak due to the cutouts and the breaks. The epoxy repair will be strong but the stone next to it will be the weakest part of the counter.
You should use a knife grade epoxy colored to match the base color of the stone. As it starts to harden you should razor blade it flush. If when you finish there is still a downward swell where the glue is at the face level you should either do a second coat of colored epoxy or a top coat with poly resin, also colored to match.
Do you want links on these products?

Glad to be of service,
Mark

[akoroma]

Thanks very much for that valuable information. Now, after glueing the two, should I use the same epoxy to glue the unit to the countertop? If not, what are the best glue type for marble.
I saw a liquid nail at the supply store that says Marble on it I wonder if that would be fine.


Thanks in advance!

[Mark D.]

Use 100% silicone to glue the counter to the cabinet.
Do NOT use liquid nails as it may bleed through and discolor the stone. Just because it says you can use it for stone doesn't mean it is good for it. If you ask any fabricator they will warn you against using liquid nails.
Mark