Not necessarily.
A diamond is valued according to its cut -- round in this case, carat weight, colour and clarity.
blue
Yes, if it is pure natural sapphire it will be worth more than a diamond.
Of equal weight, and of best quality, diamonds are worth more than platinum.
more valuable, most valuable
more valuable, most valuable
Of equal weight, gem-quality diamond is more valuable than silver.
Diamonds are more valuable than coal.
A natural diamond will always be more valuable than a lab-created diamond, given the same clarity, colour, carat weight and cut of the two comparables.
blue
By weight, a gem-stone quality diamond is more valuable than oil.
Diamonds and platinum are both valuable and expensive commodities. The worth of one compared to the other largely depends on the quality and color.
Yes, if it is pure natural sapphire it will be worth more than a diamond.
Diamond and Uranium
No, but Iridium is more valuable.
A diamond is more valuable than a zirconia, given that they are equal weight, cut, clarity and colour.
Diamond is more valuable than graphite because of it's rarity, hardness, and aesthetics when cut.
Because the round cut requires a higher quality of diamond in order to retain carat weight, these diamonds are generally more expensive than other cuts.