They are a real Escher only if they have a label that has not been added later. There are a couple known labels that are Escher stones sold by others. There are threads on this.

An Escher is a Thuringian stone and they come in many colors and honing factors denoted by the colors.
There are usually one or two on the Buy-Sell-Trade threads.

They are great hones but I would suggest awaiting the time when you can hone well to obtain one; and, since we now have synthetics that are a lot more stable and the grit is specified by a good maker, The price for a new person to honing could be a lot cheaper and perhaps more effective than buying an Escher. Any natural stone has a learning curve!

I am keeping the few Escher's that I have and enjoying some other Thuringian hones.
JMO, YMMV
~Richard