The colour of the samples was measured in three different
points on the top using a colorimeter (model CR-400, Konica Minolta
Sensing Inc., Tokyo, Japan). The illuminate C was used and a
diaphragm aperture of 8 mm and previously calibrated against a
standard white tile. The CIE L⁄ (lightness), a⁄ (greenness/redness),
b⁄ (blueness/yellowness) colour space values were registered using
a data software ‘‘Spectra Magic Nx” (version CM-S100W 2.03.0006)