hray david give good points. yes it is good to have a good master lap period. we use it for the china toppers. i don’t recommend those film laps as they flex soft surface- rounds edges of facets. your using a worn 1200 lap for pre-polish good. here we all go from 1200 directly to the TIN lap to polish, but as i have already posted at very slow speed and use diamond powder 50k and water only. yes i have two 6″ batt laps that i don’t use any more. i got so frustrated with the market tin laps not holding the diamond properly and giving me the polish i wanted. i ended up making my own. i found a supplier i could get tin blanks to bond to a master lap then machine to make ready. mine are 98+ pure tin and give a great polish and fast on all materials. i’ve got 15 of them out there being use very happily.