Detecting Beryllium Oxide vs Alumina?

[Macfixer01]

Since there is already a very old thread on this topic, it was suggested that I start a new one.

I’m doing some experimenting with trying to reliably detect BeO vs Alumina using one of those cheap $10 Diamond Selector testers from eBay.  They work by testing thermal conductivity of the material.  BeO has much higher thermal conductivity than Alumina, and diamonds are much higher again than BeO.  I only received the tester earlier today and could only find one known BeO device here at the moment for comparison, a Western Electric 416C vacuum tube.  It reads full scale with beeping on the BeO parts of the tube every time, and only partial LED scale on ordinary white or purple ceramic DIP IC’s depending how the one setting pot is adjusted.  I did get just a couple false positives though, and tests on a device I thought (might) be BeO was inconclusive.  As I said I just started working with it tonight though, and need to find some different types of known BeO devices in my scrap collection for comparison.  I’m just wondering though if anybody else has already done any work along this line?  Thanks!

Macfixer01