Answer:
6.28 mm
Explanation:
We have been given the diameter of circle shape necklace


So, the radius of circle shape necklace is 2mm
Using the formula for circumference which is:

Circumference of necklace of circle shaped is:


And as we are given that the circumference of of the earrings is one-half the circumference of the necklace.
Hence, the the circumference of the circle-shaped part of one of the earrings:

