Try them and see if you get problems. Nobody is going to make a positive ID on them without a bit of guesswork. My best guess is that it is a 1N914 or 1N4148 diode but I could be completely wrong. The voltage reading you measured depends entirely on what current you passed through the device. The 1N4148: -
So if you passed 1 mA then 0.55 to 0.62 volts is about right for a diode of this type. Also, how do you know they are not zener diodes? Diodes cost pennies and my personal advise is throw them away and buy the ones you need.
Take my word for it - you will be saving yourself time and time = money.