If you want a "wet look", then you can accomplish that by adding any kind of clear coat over your rocks. The one I'd recommend is "Gloss Sealer & Finish" made by Tile Lab and available at Home Depot. Tile Lab also makes a similar product called "Matte Sealer & Finish" if you don't want the gloss.

The reason I'd recommend this one is because:

a) It's acrylic, and as such doesn't suffer from the problem common to all silicone based plastics; namely that they will stick well to common substrates, but nothing will stick well to them. So, if after 10 years, you want to add another coat of sealer to restore the look of your rock exterior, the new silicone based sealer won't stick well to the old silicone based sealer already on the rocks. By opting for am acrylic film forming grout sealer, you avoid that problem, and the new acrylic film forming grout sealer will stick to the old just as well as a new coat of top quality latex paint will stick to an old coat of top quality latex paint. (In my apartment block, I use a product simply called "Grout Sealer" made by the Glaze 'N Seal company of California. It's an excellent grout sealer, but it's much more difficult to remove. I need to use acetone to remove it. In your situation, I'd use the Gloss Sealer & Finish just because it's easy to apply more with a spray bottle or garden sprayer, but it's also much easier to remove using Tile Lab's Heavy Duty Cleaner & Stripper.)

b) Tile Lab makes an excellent stripper for this sealer. So, if it starts to chaulk on you and you regret having put it on to begin with, removing the stuff will be quick and easy. Just buy some "Heavy Duty Cleaner & Stripper", which is made specifically to strip off both "Matte Sealer & Finish" and "Gloss Sealer & Finish". Just spray some Heavy Duty Cleaner & Stripper onto your sealer with a spray bottle, give it 20 seconds to penetrate into the sealer, and then scrub with a green or white Scotchbrite scouring pad. (Of the kind sold in supermarkets for scrubbing pots.)

c) Acrylic plastic is almost completely transparent to UV light from the Sun. One of the problems initially encountered with water based exterior wood stains is that the wood would deteriorate under the acrylic film that housed UV blockers. Companies had to up the amount of UV blockers they added to exterior water based stains to account for the fact that the binder film itself wouldn't absorb any UV light. In this case, you don't have to worry about UV light harming your rocks; they're pretty much immune to UV light.

But, rocks are heavy and therefore have a lot of thermal inertia. So, early in the morning when the Sun comes up and warms up the day, the rocks on the shaded side of your house are gonna remain cold for the first few hours. During that time, condensation is going to form on those cold rocks, and you may have a mildew growth problem there as a result. You can kill the mildew by just spraying it with bleach (bleach won't harm acrylic plastic or rocks), but if you're not having that problem now, then I don't see why a coating of acrylic plastic over your rocks is going to cause that problem to start occuring.

I would use "Gloss Sealer & Finish" made by Tile Lab, and pick up some "Heavy Duty Cleaner & Stripper" just to experiment to prove to yourself that it removes that sealer quickly and easily.

PS: (You don't need to know the rest)

The reason why porous rough materials (like rocks, concrete, sand, wood, fabrics, etc.) all look darker when they're wet is because the refractive index of water (at 1.33) is closer to that of solids than that of air (which has a refractive index of about 1.00. So, when light travels through a wet t-shirt (for example), it bends less at each water/cotton interface than it would if it encountered an air/cotton interface. Consequently, light travels in a straightER path going through wet cotton then it would going through dry cotton. Consequently, it tends to penetrate deeper into the fabric where it is absorbed. By contrast, the larger angle that light refracts through while traveling through dry materials means that a greater percentage of the incident light is refracted enough times to bend it a full 180 degrees, and so more of the incident light hitting a dry material is refracted through 180 degrees and ends up going back out of the substrate. That difference in the amount of light seen emitted from the material when it's dry and when it's wet is the reason why porous materials look darker when they're wet.

And, now you also know exactly how a wet t-shirt contest works. Since light travels a straighter path through wet cotton, it behaves more like it would if the wet cotton weren't even there. So, what you see is more similar to what you'd see if the wet cotton weren't even there.