There has been a lot of interest lately in domed Tropic crystals, so I thought I'd do a quick photo comparison. I attempted to show what they look like from low oblique angles and then slightly higher, so you can see how the distortions change with viewing angle.
All of these are genuine vintage tropic crystals except the CWP tropic 19 on the Frosty Flake. The 1665 Sea Dweller wears a tropic 39 "Superdome", the 6538 Big Gonzo wears a tropic 17 "Superdome", and the 6536/1 Mini-Gonzo wears a tropic 16 "Dome".
To start off, here's a group shot with the Frosty Flake down front, then left to right, the Mini-Gonzo, the Big Gonzo and the SD. At this point the only crystal that looks fake is the genuine 39 on the SD.
Next up is the tropic 19 vs. tropic 39, from a low angle and then higher.
Next is the tropic 19 high dome vs. the tropic 16 low dome.
Now lets look at the tropic 19 vs. the tropic 17.
Tropic 19 vs. tropic 39 again.
And now in one smooth sweep from low to high, all four together. Compare the distortions at different angles.
Et voila'. I hope this will help you decide which tropic to choose for your build, and will show the optical properties of each.