It could be argued that those two examples are good cases where the customer could be concerned about the value they get, even including the status factor. Diamonds are notoriously high-priced because of a quasi-monopoly, and high-end clothing is pretty often of poor value, quality-wise. If you like designer clothes--and you're not on unlimited budget--you eventually learn what designers/brands to avoid, because the value is just not there, even for that industry.

So this looks like a case in point, where having a rough ideas of the production cost (some parts hand-made, made in France/Italy/England, expansive material like quality cashmere etc.) is important.