Table 2: Estimated rest-frame B-V colour for the different quasar images in our sample.

Quasar	Images	B-V
SDSS J131058.13+010822.2	A	0.8
Q2237+030	A B C D	3.4, 2.1, 3.6, 3.4
SDSS J084957.97+510829.0	A	1.1
SDSS1155+6346	A B	1.5, 1.1
MG1654+1346	A	0.4
CXOCY J220132.8-320144	A B	1.7, 1.8
SDSS J0903+5028	A B	0.7, 0.5
SDSS J0924+0219	A B C	0.4, 0.6, 0.2
CLASS B1152+199	A B	1.8, 1.7
HE0435-1223	A B C D	1.1, 1.0, 1.0, 1.0
Q0142-100	A B	0.1, 0.1
HE0230-2130	A1 A2 B C	0.4, 0.2, 0.3, 0.8
BRI0952-0115	A B	0.7, 0.8
WFI2033-4723	A1 A2 B C	0.4, -0.1, -0.3, -0.1
SDSS J1004+4112	A B C D	0.1, 0.6, 0.3, 1.6
J1004+1229	A B	3.9, 5.0
MG0414+0534	A1 A2 B C	2.9, 3.1, 2.8, 2.8
SDSS J012147.73+002718.7	A	1.0
SDSS J145907.19+002401.2	A	0.9
SDSS J144612.98+035154.4	A	0.8