In terms of colour, it has been reported that most cones are entirely white, entirely red or painted red only on the stamped surface.
There also are, though rather unusual, following coloured cones:
Blue: Daressy 1893: 270; Budge 1893: 218; Pellegrini 1902: 153; Northampton et al. 1908: 35; Bruyère 1924: 62; von Droste zu Hülshoff and Schlick-Nolte 1984: # 2293; 01-052, 01-106, 01-201, 01-250, 01-260, and 01-271 in Davies's notebook; 03-039 in Macadam's Red file; 04-057 in his Green file.
Yellow: 01-087, 01-131, 01-140, 01-252, and 01-283 in Davies's notebook; 04-006 and 04-093 in Macadam's Green file; Collins 1976 [JEA 62]: 34; an example in The Royal Ontario Museum, inventory number 993X2.88, and the one possessed by McGovern-Huffmann, EC6136, both seen below.
Black: # 4 (01-006 in Davies's notebook), # 61 (Dibley and Lipkin 2009: 27), # 311 (? LM: 1973.1.450), # 371 (ROM: 963.101.3), and # 602 (? Louvre: N 707 29 (Salt nº902, CF 99)).
Generally speaking, since the outer surface of the tombs was covered with white plaster, it is possible that the cones were coloured so as to attract visitors.