It is quite lovely! I am not able to confirm with my notes when hallmarking metals started in Japan, so there may not be any marks on it to tell you if it is 14 or 18 or 24 karat gold or if it plated or just a non-plated metal.
Does a magnet stick to it? While that is not 100% conclusive, magnets do not stick to gold or silver and will attract other metals. Most of the value will be in the metal more than than the cameo itself (if it is gold or silver which are at all time highs at the moment).
It would be best to take this to a professional jeweler who specializes in vintage jewelry (not quite an antique if it was purchased in 1927) and have them look at it.
If it is ivory, they will need to tell you how it falls into the ability to sell it (or not as ivory is often something that cannot legally be sold).
Every US state and many non-US countries have their own laws which allow or prohibit or restrict the sale of anything with ivory--so you will need to know if that is what it is and the rule for where you are trying to sell it. That renders the piece valueless if you can't sell it--which is a bummer!
No one can give you a value without more info (see above) so that is why I suggest taking it to an expert.
I can tell you generally if it is not ivory and not a precious metal (gold, silver, platinum), they sell from $10-several hundred dollars depending on what a person wants and how many are on the market and if it can be confirmed who made it--which I find nearly impossible unless it is marked OR someone is a niche expert and happens to recognize it as something they have seen a lot of.
The left facing are not as rare as you think...I see them all the time. I think this is an internet myth that they are "rare". That said, it is something I would mention if I was selling it online in a headline only because people sometimes have a preference based on their personal likes and how they want to wear the piece if it faces left or right.
Post back what an expert in your town tells you!! Thanks for sharing your lovely piece!!
This type of piece was made in Japan especially for the tourist trade and may only be gold plated.
This is a link to sold listings on eBay where you can see the current value of some of these similar ones as you'll probably never see an exact match.
It would be good if you can take it to a local jewelry store for an appraisal or at least type of metal but if their review rate is too high you can try taking it to a high end pawn shop and ask about the metal.
This is a lovely piece, and depends on the type of materials it is made out of. If it truly has real gold , that alone will drive the value up. There are quite a few for sale online. You would have to have a special brooch to get a higher sale. Here are a few and what they are asking -www.ebay.com/
First let me say how beautiful this brooch piece is! I see it has sentimental value as well. I was on Etsy, and I saw that there was one, like this one, which was facing left. It was priced at $30.00.
I feel this one is worth more than that. It is just so pretty!
Have a wonderful day!