I'm investigating diamond impression mats that you can apply into/on to fondant and buttercream.

Do you use the mat before applying to the cake? Or after?

Any preferences you guys like?

THANKSSSSSS!!!

I use like the triple diamond cutter to imprint the pattern on the side of the cake, and then go over the lines with a quilting tool.

I use the cutters too, and then go over it with a tool to define the lines. If you try to use fondant that has been embossed on a mat, as you try to smooth it on the cake it will mess your embossing up, learned that one the hard way lol. I actually make my own tool for embossing diamonds, I get the corner tape used for hanging sheet rock and strip off the paper and use the metal strip in the middle to make tons of stuff, You can get a huge role of it at Lowes for $20. It's easy to bend with pliers, and it has a sharp edge for cutting or you can use the other edge for embossing. I use hot glue to keep the sides connected. This way you can make the right size for the cake yo are making. Hope this helps.