Hi, Charybdis - yes, you are correct that this is referred to as a gorget, pronounced "gore-jet".
It started out in ancient times as a full metal collar, surrounding the neck and upper shoulder area as a part of personal armor to protect against a sword attack to that area. Over the centuries, it evolved into what you see above - in this case, the WWII German variant, most commonly used by their equivalent of the Military Police. After WWII, both East and West Germany's continued the practice, and I believe they do to this day, post-reunification. Other nations' militaries throughout the ages have used similar devices for decorative use, even after the employment of melee weapons had become obsolete.
If you do a Google image search on the word "gorget", you will see a ton of very cool-looking variants. And yes, I would bet my next full paycheck that the Colonial Warrior decoration was based precisely on this concept, especially due to its ancient origins. The German use of this device would make sense, as their leadership was heavily interested in ancient alien influence on the Aryan root race, from which they claimed pedigree. Any allusion to ancient alien/astronaut involvement would have been played-up to reenforce that mythology (regardless if it was true or not
).
Unfortunately, as official records from the BSG costuming department are virtually non-existent, there is likely no way to absolutely confirm that this was the plan.
I'm still waiting for the day that someone from costuming will come forward and say, "yeah, I came up with all the Colonial insignia - what do you want to know?" but I'm not really holding my breath on that one.