Yes, Cartier's Tutti Frutti is a good example. You can have that "overall style" copied aka "without the name" - and it will probably be a hard sell - no matter the quality. Whereas a Cartier piece
might raise in value at some point. I say might because it's quite simply a bet on future, a risky one. Currently people feel everything is possible in jewelry/watch world, see:
https://www.hodinkee.com/articles/p...00a-only-watch-2019-most-expensive-31-million
GIA (and similar) reports are only worth so much and, basically only as long as they are physically attached to the stone. Luckily we have laser engraving. At least as long as you have some basic trust in the source. If you can't identify/rate stones yourself, stay away from offers to source something for you from unverified sources. Especially if you have no means to verify the report(s) fits the stone(s) you got.
I will say this: Buying and selling diamonds as amateur is like swimming in a pool full of sharks. With sea mines at half-depth and some venomous sea snakes in between. Choose wisely who you trust and always, always verify.
Jewelry, without a name attached, will almost always sell below what you paid for it. Exceptions confirm the rule.

And the only factor determining a price when selling is the actual cost of material and stones. So if you use (truly exceptional) stones, they will decrease/increase in value according to current market within their league just as the other materials will. Don't expect the work being a big (or any) factor when selling. Again, exceptions confirm the rule.
(Highly) Personal rating:
1. Graff
2. Cartier
3. Harry Winston
4. Tiffany & Co.
5. VCA
If, like you say, you're not an experienced buyer/seller, stick with the big houses and you might eventually get lucky. Everything else will be ending up a disaster, especially when sourcing stones from halfway round the world without proper knowledge and means of verifying. Not to mention many other risks.
If you don't want to go with the big names, ask and look around for a local professional you can trust. Go with your gut feeling, if it doesn't feel right, it probably isn't.
Try to gain some experience by having someone you can trust show you some stones and their ratings/reports.
So, yes, jewelry "with a name" will not only hold value better but there is a chance of value increasing over time in accordance with market/sentiment.
Jewelry "without a name" will generally fetch lower resale value. It's determined by quality of materials, only - and those obviously again in accordance with market/sentiment. You will almost always loose on the cost of work.
Provenance is important is both cases, but especially with jewelry "without a name".
Custom made/ bespoke jewelry should be for oneself to wear and enjoy, then it's the best and most enjoyable experience. If it's about speculation on resell value - that, one can have much easier, and with less baggage attached.
I can only strongly advise against using a +- one million jewelry project to test waters. I can only say it again, it would be bound for a disaster. Go with something that feels right from the get go - from a reliable source.
Hope this helps.
Kind regards,
Oliver