Ann: Copper-Gold Porphyry System Identified at La Florida, page-47

It's not as simple as slapping a number on things as context is always key. For example, a project with high grades but severe geographical barriers or large amounts of overburden will potentially be un-economical, despite the high grade. Conversely, a low grade bulk tonnage operation right at surface, with infrastructure available, short distance to port can be ok under the right circumstances.

I mention this as a disclaimer to my answer and I'm sure others will chime in with their own opinion, but a good starting base to assess things would be to view it this way:

0.5% and lower Cu : low grade
0.5% - 1% Cu : Medium grade
1% plus Cu : High grade

This is not investing advice and you should consider this your starting point to then do further research. For example, 2% of copper for only 1m vs 1% of copper for 10m.

Perhaps someone with a stronger geological background can add on top of my answer and go more into depth for you.

Side note, there are some nice historical grades on this stock.

Also, what is considered high grade has been changing because it's getting harder to find good copper deposits.