Hi! This is really nice to hear that you have made progress! On our shop, we have created an even more detailed taxonomy for the ingredients. It is part of an as of yet unreleased search engine based on Shopify instead of Algolia. We have not released it yet. But it includes very fundamental aspects such as: physical form (liquid, solid, slurry), color, etc. Let me get back to you early next week with full comments. Also, in our case, the synthetic/natural is not part of the taxonomy but is rather a property because this is very contencious, we call it the "pathway" (this means "how it was obtained").

Hi guys, here are my comments:

• Synthetic vs Natural: this is a very, very, very contentious issue because no consensus exists on a definition of "natural". Some argue that if a molecular species can be found in nature, any of its enantiomers is "natural", even when a specific product is obtained via an in-vitro chemical reaction. Further more who's to say in-vitro reactions based on enzymatic processes that occur in nature, sometimes involving the exact same micro-organisms, are not themselves natural? This distinction has been enabling a lot of fraud since the industrial revolution and this taxonomy is an opportunity to fix this. We strongly suggest to merge the two taxonomy nodes as one and move this dimension/facet/aspect as a value/property instead. We propose "pathway" for the property name with two possible values: "natural" or "synthetic". And the description for the two possible values is as follow: "natural" is used when the substance is obtained solely by physical separation (distillation, tincturing, expression, etc.) from biomass (matter harvested, culled, secreted from/by living organisms) and absolutely no chemical reaction has occured at any time during the extraction. "Synthetic" is anything else;
• Perfume kit items included: Instead of "perfume", "perfumery" should be used. And instead of "items", one should use "instruments" because that's the term in common usage to refer to anything else than ingredients. You could also simply say "Instruments included". We should have "spray caps" and/or "spray pumps" and/or "sprayers" and/or "flacons" (flacons are decorative containers used to store the finished perfume blend and "bottles" are for WIP substances, incredients, bases, etc.);
• Fragrance base type: "base" refers to something very specific in perfumery and should not be used for anything else. What you list as possible values for this property are called "additives" and are any "solvent", "solubilizer", "stabilizer" added to a perfume ingredients. And the list is very long before we get to "others". I could provide suggestions for this if you want. Also, the solvent is usually considered seperately. See "concentration" below.
• Fragrance family: this is very subjective and varies from one retailer to the other. As for "synthetic" vs "natural", there is absolutely no concensus on this. But unlike the "synthetic" vs "natural", it's not a binary property and it should not be formalized for it to be useable. For instence Amazon has tried it and it's a mess: it confuses more than it helps. And we don't use "fragrance" for "ingredient", we use "olfactory". So it's "olfactory" family.
• Concentration: nothing, absolutely nothing is ever "pure". But not everything is "diluted". Usually, this is an optional facet: with the "percent" dilution and an acronym for solvent is specified: 10% SDA (specially denaturated alcohol), 1% DPG (dipropylene glycol). So there is a "concentration" part and a "solvent" part. And it's called "solution". And when it's not been diluted, it's left blank.
• Perfume note type: this is called "volatility". Sometimes it's described as you put it: base, middle/heart, top. But it's also sometimes and more accurately described as how long you can smell it on a paper strip: N seconds, N minutes, N hours, N days, N weeks, N months. Base, middle, top are more marketing terms used to describe perfumes and are less relevant for perfume ingredients;
• Perfume note function: this simply should be left to the description or as custom metafields because it's even more subjective and non-descriptive as the other aspects above;
• CAS Number: you didn't put it as a property, but it MUST be there. Everything from essential oils to single molecules have CAS numbers and it's the only universal way to unambiguously refer to a perfumery incredient. Bases or new ingredients (sometimes only temporarily) don't have a CAS Registry Number and "Not Available" and "Not Applicable" should also be valid values on top of the formal regex-able CAS number. But this is an absolute must.

I'm available to consult for free on this but please, please let's do this right!

Thanks!