I have had one of these on my druid for a long time, and it used to have 23 charges on it. One day I logged on to find it with no charges. I didn't really care too much, so I just didn't think about it really. I went to buy a new one today just in case I wanted to use it, and all 3 that were listed in the bazaar said they had 20 charges on them. The one I bought did not in fact have 20 charges, but zero. So, just in case anyone is looking at this, save yourself the trouble and find a Silvery Mask.
I just got one myself. Didn't know what it was and have a better thing for my cleric's secondary slot now, so I thought about selling it. It doesn't have 25 charges of Identify though...I think it has about 5...maybe a few more, I can't recall at the moment. What would be a fair price (I'm on Sol Ro)?