User blog comment:Blackshadownaruga/Lao shan rubies/@comment-2037363-20100508164017

It's a 3% Carve chance from the Ash Lao-Shan. It's also possible to get it as a reward item if you: Break it's Horn (3%) Wound it's Back (2%) Break it's left/right shoulder (2% for each)

http://monsterhunter.wikia.com/wiki/MHF2_Boss_Carve_Guide_(by_Kawakami_Hanabi)#Ash_Lao-Shan_Lung