Phones and tablets are media consumption devices. Not media creation devices. No matter what manufacturers will tell you - touch input, small screens and "simplified" (read: crippled) operating system/controls etc. are a trash pick for this kind of work. Freehand drawing, okay, but that's it. This kind of work is to be done on a traditional desktop computer with a big, high-res and color calibrated screen, proper accurate input devices, and sophisticated software.
I would also highly recommend hiring a professional designer. You are going to slap those inlays/labels on chips, and those chips will cost you. Ceramics are expensive, CPCs even more, so you want to make absolutely sure the design is very refined. There are so many things to consider and look out for... If you are not even a hobbyist designer and have zero skills in using vector drawing software yet, you can sure do some rough mockups but I would not put anything that comes out of that on a chip. It can be good however to show a designer what you want.