Sourcing powerful magnifying glass

Many years ago (20+) I used to live next to a (industrial) lens factory,
and our neighbour who used to work there brought me a damaged magnifying
glass. See a couple of photos he
http://tinypic.com/r/294nrc7/7
http://tinypic.com/r/x1hzzs/7

It is much more powerful than the average ones that you can easily get,
and I have used it ever since.

I now want another similar one, but looking online doesn't seem to bring
up anything.

Any pointers will be much appreciated.

TIA.

PS: the factory no longer exist, and is more that 5000 miles away anyway…