How do you explain these diamonds that are underpriced?

[zz00ter]

If market pricing is rational, then how does a diamond exist at this price?
It seems like an unusually low price to me.

Price = $6,359
HCA = 0.8

Carat Weight:1.30
Cut:Excellent
Color:I
Clarity:VS1

http://www.b2cjewels.com/dd-4173179-1.30-carat-Round-diamond-I-color-VS1-Clarity.aspx?sku=4173179&utm_source=pricescope.com&utm_medium=referral&utm_campaign=pricescope.com

 

[Mayk]

I'm not one of the experts but with Strong Blue Fluorescence it could be cloudy

 

[Ashleigh]

You can ask b2c why that diamond is priced like that. They will point out the diamond's flaw or supplier pricing error. I think it's most probably the strong fluo.