This is a first Apollonian Necklace (the second is here).
An Apollonian Circle Packing starts with three mutually touching circles with their circumcircle. Then the remaining spaces are filled with circles that just fit. This leads to a beautiful pattern of circles. This necklace piece is part of a random Apollonian circle packing.
This piece was designed in the mathematical computational software Mathematica.
This piece does not come with a chain, but there are *circles* to which a chain can be attached.