Bone's definitive marks vs ivory are evident using a loupe.
Personal opinion I know, but none of my objects are hot needled, or chemical tested by me. I was taught early on to use my senses to Identify materials. Beyond magnification that could include holding in a warm hand, then observing any material odors, or even the sound with a light tap on glass. Some objects are significantly rare, perhaps a one of, a prototype, or historic, and as such, test holes, and chemical abrasions disrespectfully devalue, possibly initiating, or accelerating age deterioration. imvho per my observation.
Edited to include, hot needle accidentally not to ivory/bone, but celluloid, it's poof > gone. Most people are ga-ga over phenolic's, or modern acrylics, and have yet to appreciate the beauty, depth, and versatility of celluloid. There's a lot of celluloid in the pen world, for a reason. Much still functioning handsomely after some 70 decades. Simple exception, excessive Heat is not its friend.
Sorry this is wordy, Goudy's comments and links ably covered the ID, this sharing is for new ones who might see Hot Needle, and test unknowingly.
Edited by pen2paper, 06 September 2015 - 04:21.