Kristen, This may not be spelled correctly, but Fresnal lenses are the
lenses used in lighthouses. they are primarily used to focus a beam
of light from a source that was historically not too strong a light.
(oil burning lamps in the early days.) and direct this beam out to sea
for ships to see, and be warned of danger in that direction.
Recently I have seen some discussion of gem cuts using the same
principle as these lenses. I cannot for the life of me remember where
I saw the drawings of these cuts, but they seemed to be relatively
complex for gemcutting, and I would guess that I would not cut one for
less than the $70-$100 your friend was told about.
I know this is a bit sketchy , but perhaps will be a lead for you.
Facets of Newberry