Basic math - am I losing my mind? CTW question

[Mekp]

I've been in contact with a jewellery designer regarding earrings i want made.
I want 5 x 0.08ct stones on EACH earring for a total of 0.8ctw.
I just got a response wanting clarification, stating that a total of10 stones at 0.08 each equals 0.35 ctw, not 0.8.
I am so confused. How can I explain this better? I am sure it equals 0.8 but maybe I'm not describing it well? Or have my math skills gotten that bad and I'm wrong?
Help please!

 

[Karl_K]

5 x 0.08ct stones on EACH earring for a total of 0.8ctw
Is correct.

Their reply makes no sense.

 

[lillibear]

Have you checked your prior emails to see that you sent the correct numbers?

 

[Bron357]

You are correct.
Recheck your correspondence with the vendor.
0.08 + 0.08 + 0.08 + 0.08 + 0.08 = 0.40. = 1 earring.
0.40 x 2 = 0.80 tcwt.

 

[MWM]

Someone is fixated on 1.8 mm round diamond size. There is a hitch in communications.

 

[Mekp]

Thanks everyone! I'll try again.