This master marble is from I've had very few of these to sell over the years, they're hard to come by and hard to let go of! Mark's Geometric series, each one of these a sweet piece of marble history! These incredible patterned marbles are made using the graal technique, with black glass layered over white and then the pattern meticulously laid on the marble and blasted away, then completed with a thick layer of crystal dipped and laid over the pattern which makes the whole thing absolutely pop in hand. The results are WONDERFUL, and these are some of the most magnificent marbles you'll ever behold! I've had very few of these marbles to sell over the years, as they are hard to come by, and even harder to let go of. I've had very few of these marbles to sell over the years, as they are hard to come by, and even harder to let go of. This gem here is simple....and wildly complex. So nicely done!! Mark made 2 versions of the Zipper, one goes to the left, one to the right, both avilable. Signed 'Matthews 2009'.