If I focus myself enough and not take it too fast, I can easily spot stones while sorting out cacao defects. I know I need to. First, I never want to feed myself and my customers with ground stones. Second, it may affect flavor. Render the product inedible in extreme cases. Third, it damages equipment.
What if a stone was missed during the selection process? My two old and inefficient grinders almost always tell me. Grinding nibs included with a stone or two produces a sudden cracking sound for few seconds. Luckily, it became part of the liquor. In case too hard, the annoying sound won’t stop. Grinding process should be halted. Disassemble the machine and look for the hard to find stone among the partially ground nibs. A waste of time, quality reduction and possible machine damage.
Stones are small in most cases and pass through the three layer sorting screens that I am using. Larger ones are easy to spot. So, no more worries. However, sometimes, the culprits disguises themselves as cacao beans. Rare case and happened only twice.
For this second time, I had free time to get picture and post it here.
Its shape resembles cocoa beans but the green shade made me suspicious, so I looked closer. It is a hard stone that perhaps do damage my current grinder.