The results have a fairly large error due to the accuracy of weighing (1 gram), but if you are interested, please:
I chose 4 sections of wires A, B, C, D, 200 mm long each. I weighed the entire length and then the insulation and copper separately.
A / Wire 3x1.5mm?, stranded, double insulated
B / 2x1.5mm? cable, double-insulated strand
C / Wire 1x2.5mm? single insulated wire
D / Telephone cable 14x0.2mm? with double insulation.
Results:
conductor --- total weight --- copper weight --- insulation weight (weight in grams)
A / ------------ 18 ------------------ 7 ---------------- - 11
B / ------------ 14 ------------------ 5 ---------------- - 9
C / ------------- 6 ------------------ 4 --------------- ---- 2
D / ------------- 11 ----------------- 4 ---------------- --- 7