Chemical coatings and wax used to be applied quite often in an attempt to reduce maintenance and/or change the shine or look of the stone, but most often these coatings add little benefit and create more problems (and maintenance) then they were meant to solve.
Topical conditioners and polishes can be used to enhance the shine, but such products (the good ones anyway) don't form a film and are only temporary... they wear off with use and cleaning.
As much as possible you want to leave any stone in a natural state.
Applying a marble & granite sealer is often beneficial, but this does not change or affect the look or performance of the stone (except to drastically slow down absorption of staining liquids) since the sealer works below the surface.
The problem with coatings and waxes is that they cover the surface, so now you have a layer of something that is not stone. The required maintenance is then dictated by the needs of the coating and not the stone.
And is some instances a coating can actually cause the stone to decompose by not letting it breath.
Many mistakenly believe the shiny marble surface comes from applying some type of product or "finish".
When speaking of marble the "finish" is part of the stone and not something put on the stone. The "finish" refers to the type of surface treatment given to the stone... meaning a shiny "polished" finish or a more dull but smooth "honed" finish or a somewhat rough "tumbled" finish, etc.
The various types of finish are created on the stone itself with different physical methods. A finish can be worn away from use, foot traffic, but it's not going to "come off" like a coating will. Learn more about how to polish marble (click here).
You need to strip off whatever is on the marble surface, see what shape it's in and go from there.
Who knows what the marble surface and finish will be like once removed, but it may need nothing more than a good marble cleaning.
I have a marble coffee table with cracks in the finish... not in the stone. I do believe it is real stone not cultured. What to do to repair this cracking.
Let's first clarify what is meant by the "finish" when speaking about natural stone. The finish is actually part of the stone itself.
However, you state that the marble table has "cracks in the finish... not in the stone".
This clue likely means that you have some type of coating that was once applied on top of the marble.
Yes, in other applications such a coating would be considered a "finish", so I explained to make clear the difference with natural stone.
The marble table surface finish is not "applied" or "put on" the stone. The "finish" on any stone whether honed or tumbled or flamed or polished is simply a matter of working the stone with tools and abrasives to get the effect you want.
For example a shiny "polished" marble finish is made by intense friction using special abrasives to wear the stone into a smooth, mirror-like finish.
Generally marble polishing of large slabs is done on specialized industrial machines. Your table was likely made from such a slab.
It may have become dull at some point due to marble etching and someone put a coating on it attempting to make it shiny again.
When polishing stone manually it's a lot like sanding wood only much more difficult to do well.
If you do have a true crack, it is in the stone. It may not be all the way through the full thickness of the stone, but in the stone nonetheless.
Of course, you could have a scratch, which if severe enough you could see and feel. And you could have an old coating or wax that is now dried out and cracking.
Cracks are a different matter and it depends on the type. Are these actual cracks in the stone or possibly cracking of a surface coating or even just scratches?
You can't really "buff out" a true crack in the stone. If the crack is large and there is separation, then you could perhaps apply polyester glue like Akemi to fill and or support the area, but obviously you can't "remove" a crack. Even when repaired it will always be visible.
So, this is something I'd have a marble repair and restoration professional look at.
Now if these "cracks" are actually scratches, then yes.... they can be repaired using ETCH REMOVER / Marble Polishing product (link above) to buff them out on a "polished" (shiny finish) marble surface.
Cracking of a coating is another issue entirely. Waxes and surface coatings get old and dry and can show cracking, scuffing and/or discoloration.
Waxes and coatings are not commonly used anymore and should not be. They create more maintenance issues than they solve.
However, if this is the case with your marble countertop, then the coating itself must be stripped off the surface using the Deep Clean Stripper / Degreaser (see link above).
Once the wax / coating is removed, then you can assess the true condition of the marble vanity.
For the sinks... if the stains and cracks are in the sinks themselves, I'd consider just replacing them unless they are particularly unique.
Again, if the sinks are marble the stains can be removed just like on a marble countertop (unless very deep and old) and scratches (not cracks) can be removed with the paste.
This would be cheaper than replacing the sinks or professional marble care, but it all depends on how severe the damage is.
I'd start with the above DIY solutions and then call in a pro if necessary.