Product itself is of a nice quality, and in general I would be pleased. However, basic quality control was not used before sending me the product. All of the stones are meant to be yellow, to go with the command theme. Unfortunately my center stone appears brown instead of yellow. When I asked Holzkern for an exchange, they were happy to do it; but they would charge me a 20% penalty to exchange the product....without any further guarantee the next stone would be any better. If you are advertising a specific color, and yes natural stones vary, your quality control should catch stones that do not match the criteria of the product for sale. I own a product I do not like, and I will certainly share this negative experience in the Trek community.