I found a silver ring that was black from time at about 10 to 12 inches the other day. I know it was deep because I had the volume up high and could barely hear the signal. I know it depends on the conditions of the beach or area that you hunt like Sandman said. Most targets seem to be from 0 down to about 6 or 7 inches. That seems to be about the standard depth for most detectors for coin size. My experience is when I have to dig beyond one foot down it has always been a can top. It is one of the things that I should have known because it was very loud, almost blasted out my ears when the coil passed over it. On the wet sand, out of reach of the waves, one time I got a faint singal that I kept digging down to at least 12 inches, maybe 15, and turned out to be the bead from a fishing swivel.
Just as a side note, I have found two gold Figaro chains with my Excalibur 1000. Neither one had a charm on it. All I can remember about finding them was that when the coil passed over them it made a broken sound. It wasn't a solid sound like a coin would make. They both were down maybe 3 inches (just an estimate) and when I passed them under the coil later they made a different sound from when I found them.
You are going to fall in love with your Excalibur. You will see. There are other great machines out there but nothing beats the iron feature. I still have never dug a bobby pin, sparkler wire, or other small piece of junk wire or iron. (That is running it in Discriminate mode, on 1)