Sorry it's our negligence that we did not correct this in the features and the user manual.
But D10 and EX10 use better impact-resistant glass for the lens with dual AR coating, so even without the diamond coating, it can be really durable, and has even higher light transmittance. Latter NiteCore products will all use this lens.
So, the glass lens of EX10 has equal sides, you can put it either way.