2 dollars
1 carat = 200mg
The cost of Platinum diamond earrings will vary greatly depending on the carat weight of the diamond. As an example for prices, 1/2 carat total weight start at about $1400 but a 1 carat total weight sells for approximately $3600 per pair.
About $800
1 carat = 0.2 grams
1 carat equals .2 grams
$15.00/carat minmum to $200/carat depends on quality of the gemstone
1 Carat = .2 grams = 100 points
Given the high number of diamonds limited by the low carat weight in your question, the cost of the diamonds might not be so much a factor as the quality of the setting into which they are mounted. The clarity quality that you describe wouldn't be so visible in diamonds weighing less than a quarter carat (.25 carat) each.
200 mg
A diamond is valued by its cut, clarity, carat weight and colour. A local jeweler may be able to give you a precise answer, given more information about the stone.
A round GIA certified 1 carat H color and VS1 clarity “VG†cut diamond is worth approx. $4,500. You can go down on clarity up to SI2 but an eye clean diamond which will cost you $3,800.