While quartz is cheap, I do not agree that’s its the easiest stone to learn on… quartz can certainly give one difficulty in polishing. I would recommend topaz and learning to polish on a batt lap with diamond. Quartz is nearly in one of its own categories when it comes to polishing, and the old “beginners” stone just doesn’t make sense anymore. Leave quartz, cerium or zirconia and the “hopefully” darkside lap for when you’ve learned to enjoy the basics of cutting and polishing with standard diamond. Preferably diasticks from Gearloose and his batt lap. Just my 2 cent, but supported by many that teach today.