It depends for me.
My e-ring upgrade is in a 6-prong Tiffany style setting. Should no jeweler ever be allowed to use that particular style setting because Tiffany's came out with it first? I think that's a bit extreme.
Another example is the Harry Winston baguette setting. I highly doubt I will ever buy a HW setting and diamond. But I love that particular style, so I would have no problem having a jeweler custom make it for me.
However, I wouldn't wear a replica Love bracelet, for instance, because it's very obvious what it's copied from.
I agree with whoever said they would rather go to a jeweler and have something custom made for based on ideas.
This is the hard question

But I tolly agree with Queennadine.
And I have the ring look like tiffany setting .
Which I know that tiffany also has the same like this but I've never ever thought just for a second that it's a copy style from tiffany.
That's not like you wear a fake bag.