Crystal headphone cable is made with 8 wires of silver plated copper litz braided, each wire being 1.8mm results in a thicker headphone cable, this cable can be finished in a splitter and connector colour of your choice.
 
Main body 7mm
Headphone ends 4mm
Wire type-  silver plated occ copper litz 
Each wire diameter- 1.8mm
Headphone type- Any full size double sided entry
Flexibility- 9/10 
Colour- Light blue
Connector colour- Any