khatsphleas on the ebay forum found a very pretty and unusual duette type pin. It had the two pieces the fit on a frame, but the separate pieces didn't have the clips that you normally would expect to see. So, how the heck could you use the two pieces once you take them off the frame?? that was the mystery!
The pieces were marked with patent numbers, so that seemed a good place to start to try and learn more about whether there was something missing, or perhaps some manufacturer just stamped phony patent numbers on a pin to make is seem vintage.
The pin had two patent numbers, both utility patents. number 2050804 and 2066969
Here are some photos of the set (thanks to khatspeas for allowing me to use her photos!)
Here's a summary of what we learned and how khat solved the mystery!
The first patent number was a patent by Alfred Philippe, issued during the time he worked for Trifari. However, the patent describes spring loaded clips that would be attached (although he does say that his description is only one example of how it might be used) and also described very clearly that one important feature of this particular patent was the use of "resilient protusions" that help hold the pieces to the frame. In comparing the patent drawings to the actual item, it didn't seem like a very good match (at least to my eye). But khat pointed out a bit into our research that while it doesn't match the drawing, it DOES match the functional idea of the patent!!!
drawing from the patent with the notches circled. (The little protrusions snap into the places at no 22 on the drawing to secure the pieces together)
photo of khat's piece where she showes how it does have the little protrusions that snap into place. They look different from the original patent drawing, but the important thing with a utility patent is the function of the item, not the look of it. So it seems a good match!
The second patent was for the pin mechanism. The main function of that patent was to show a way to make a pin by using a single piece of metal and "folding" the two ends to make the needed components. Khat noted that her pin did seem to be made that way.
drawing from the pin mechanism patent:
Digging further, we found a wonderful research page on the Researching Costume Jewelry website that showed lots of different mechanisms and versions of duette type pins. For info, Trifari used the term "clip-mates" for theirs. Coro used the Duette term. Duette is often used generically, but really only refers to Coro's version of separable items.
Sure enough at the very bottom of the web page there were some pictures of items labeled as "other" and "mystery" interchangeable clips. They also had those same patent numbers and looked just like khat's pin!!! Then khat saw it!!! yoohoo! There was the answer to the mystery of the missing clips! Some of the pins with this arrangement have separate independent (not permanently attached) clip pieces that hook into the separated halves of the pin. So for khat's pin, it seems that those clip pieces are just missing. Now we are all wondering how many fun versions of this convertible design are out there!
The one part of the mystery that remains is that it is not possible to absolutely to confirm that these were made by Trifari - at least based on what we found so far. It seems very likely that they were, since they are marked with a Trifari patent number. However, none of the examples we've seen so far, are actually marked with any of the Trifari brand names. I have read however, that on early pieces it was not unusual for makers not to mark their items with their name. Anyway, If you have found one of these very cool sets of pins, or another version, it would be very reasonable to say that they are marked with a patent that Alfred Philippe obtained while he worked at Trifari .
notes: most of the examples of items marked with the Trifari patent, look very similar to the patent drawing, in terms of how the sliding mechanism and resiliant notches work. So, there remains a small mystery in wondering when or why they used the version seen on this pin. Perhaps we'll be able to find some period advertising to help explain that part!
update: I received an email that described that these could also be worn as hair ornaments!