Diode

I have some diodes that have
ITT
Q-331
105
written on them, cathode stripe is to the left and it has a forward voltage drop of .251 on a Fluke 87.
It appears to be glass, white with black stripe, about 1/8" X 3/8 + leads.
Can any one tell what it is and how it can have such a low forward voltage drop.
Thanks
Kinarfi

The lower forward drop is likely because it's a germanium diode rather than the silicon diode that you're used to dealing with. A forward drop of around 0.1 to 0.2v would indicate a hot carrier (Schottky) diode.

Thank you, I do believe they are Schottky diodes, I was testing some other diodes that I knew were schottky and these acted exactly the same.