Good topic!
 
A number of years ago, the Philippinos were turning out fake dwarf
Cypraea guttata and they were beautifully done.  They were (I believe)
actually C. pyriformis that were painted. My wife has two in her
collection (in fact, I'm looking at them right now!)
 
I've also recently seen a fake Conus hirasei (Don Pisor has it). Other
fakes I've seen include Cypraea aurantium, C. hirasei, and C. sakuraii.
The latter was so well done I was completely fooled until it was pointed
out to me as a fake.
 
As for repairs, a certain Conus excelsus comes to mind. The entire spire
from the shoulder up was rebuilt. I've seen complete wings of Pterynotus
loebbeckei reconstructed and a Homolocantha anomaliae which was more than
50 percent fake. The most common repair that I've seen is with
Conus gloriamaris where breaks have been filled in and the missing
pattern painted on. Considering that the initial reason for faking shells
was profit driven, the practice truly has become an art form.
 
Although none of us have seen the fake rice-paste Epitoniums of legend,
the story is so well known that we might be premature in dismissing it as
false rumor and giving up the search. After all, there is no real proof
that the Hanging Gardens of Babylon existed, either, other than historic
rumor.
 
Kim Hutsell
San Diego