My 1991 Scott Specialized Catalogue for Canadian Stamps lists four colours: Scott#44 is grey, 44a is blue grey, 44b is slate and 44c is violet black.
My benchmark for turquoise is the Santa Fe Palace of the Governors stamp (1960 US Scott#1031A). Bw's bottom stamp appears to me to be 'approaching' it rather than the colours listed above and the
ebay depiction even more so.