Our modern clad will always flash a 95 on the screen even if the numbers tend to settle more realistically on the crappy steel that they are made from. Surface loonies will sometimes sound like can slaw, so it's up to you whether to pursue that. If they are under the surface you are back to a 95 on the screen.
My general rule of thumb for coin shooting in Canada is to dig anything that flashes a 95 even just a couple times. Crappy zincs never do. More importantly, listen to the tone. Coins are smooth. Aluminum is harsh.
I've also dug 5 rings with my Deleon, 3 of them silver. Every one of them left me no doubt as to dig or not by their smooth tones. Remember, the Deleon is a Tesoro, so you want to make the audio your number one resource. Tesoro has the best audio out there, IMHO, so don't ignore it. Use the screen as a secondary tool if you feel like it.
The Deleon is a great machine, and probably one of the most underrated machines Tesoro makes. I've had a lot of Tesoros, and a lot of other detectors, but this Deleon of mine is by far my favorite ever. The Cazador is going to have to be one helluva machine to make me put down my Deleon.