Bonsai_Pottery

I found some very attractive bowls that need drainage, support holes. The problem is that I have never had success drilling and not breaking. I did some huge 30 gallon Chinese fish bowl(?) from Target many years ago but they had rather thin bottoms, glazed on both side. Used them for bonsai adult trees and was successful. But they all got infected and I got depressed and threw everything away. The bowls I want to drill are glazed on inside but base/bottom terracotta. They've obviously been fired and are pretty hard; much harder than flower pots. Drills sold at BB stores heat up, turn red and melt. Specialized bits? Suggestions? Many thanks, happy trees.