Graphene was once a theoretical substance. When graphene was finally able to be made in larger batches, it came about as the result of oxidation. Now there is graphene oxide, a black, inky substance that can be used in printers of both the 2D and 3D kind.

It is nearly invisible because when printed, it is only a single atom wide or thick. Even when layers are created in a 3D printer, the graphene oxide barely becomes visible. It is its unique single-atom, single-layer thick properties that make scientists think that graphene oxide powder could be the key to invisibility or cloaking on an entirely different level than previously imagined. Here is more on that very subject, in case you want to buy your own jars of this stuff for the future development of invisibility or cloaking technology. 

Its Reflective Properties 

If you were to use a 3D printer to put down a single layer of solid graphene oxide, you would only be able to see it by shining a flashlight onto it. Even then, the slight reflection you would see would not reveal much as this clear substance would bounce back a picture that looks so much like the surrounding material. Imagine applying an entire coat of this stuff to a ship, and then having that ship reflect the surroundings rather than an image of the ship's hull. Now you have achieved near invisibility via a clear but reflective substance. 

A Cloaking Application

The concept of cloaking seems a far-fetched one, yet, it is not that improbable. The graphene oxide could produce a sort of cloaking, but the graphene would have to be applied in a thin, non-washable layer over an object. As for activating its cloaking properties, it would seem that its conductivity response to electrical impulses would fit nicely into this still semi-theoretical technology. 

Detectable but Indestructible

Graphene oxide is still in the experimental stages, although there are definitely some scientists toying with the cloaking and/or invisibility applications. The substance is detectable, if you know what and how will detect it. However, it is indestructible, which would also lend itself very well to protecting ships, soldiers, etc. The tubs of powder that you can currently purchase are extraordinarily expensive, but you could certainly try a few experiments of your own if you are willing to try. Just be really careful where you spill this stuff, as you may not be able to remove it.