How do you guage per Caret price from the range
Are you asking how to narrow down a price per carat when the values are given as a range? For example, a heat treated ruby with good color that weighs 1 ct and has VVS clarity has price per carat that ranges from $3,000 to $7,500 per ct. That’s a pretty broad range. The blunt answer for how to narrow that down: it’s a judgement call. That range represents actual prices, which can vary considerably. If you’re buying, you probably favor the lower end. If you’re a vendor, you probably favor the higher end.
Some price per carat values represent a broader quality range. For example, the price per carat range for a 0.25 ct top color Colombian emeralds with VS/SI clarity is $2,000 to $5,000. In this case, it would be reasonable to expect an SI clarity stone to be closer to the 2000 end, and an VS clarity stone to be closer to the 5000 end. However, it’s still a judgement call.