I don't mind paying for a quality piece. It's just that the piece that was recommended cost $18,000 and I honestly wasn't intending to spend THAT much for the necklace. I guess what I really was wondering was whether the specs I was looking at (SI1-2, H-I) were good enough for a piece like that and if not, how high should I go? I know generally those specs work for everyday studs but may not work for an engagement ring per say. I'm just trying to get a fair idea of what I should be looking at and what would be a fair price for what for me would be a significant purchase.
Those specs would be fine assuming that's really what they are. Buying from a reputable seller and from someone who can "prove" to you that you're buying what they say you're buying is important. I don't think buying a brand is necessary to get quality.
Have you seen stones of that grade range in person to know your threshold? Some folks don't mind that, some can't handle it bec they know it's "that low in clarity". Some folks deliberately choose it bec "why pay for what you can't see"? Educate yourself on color, clarity and cut quality so you can identify what you're buying so you're not as reliant on the seller.