What is the latitude of (Crystal Archive Fujicolor) paper?

I made some prints several days ago in the lab. The photographs were low-key, lots of deep blacks. The background was 100% black but the shirt was lit and was more like dark-gray. However, on the prints the dark shirt almost merged with the background...
In terms of RGB 0-255 values, background was 0, but the shirt was from 15-20. Still, paper couldn't take that.
So my question is - what's the latitude of that paper and what RGB ranges (from low to high) is best to avoid when printing?

Thanks!

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