I have to admit I am not very knowledgable about Nacreous clouds, though I am positive I see them all the time in Iqaluit. Mostly during the day shifts and often in the morning as the sun is rising. In an effort to learn more I turned to the International Cloud Atlas that we keep in the station. It showed me I was most likely just seeing irisation on the SC clouds.
"Nacreous clouds resemble Cirrus or almond-shaped Altocumulus. They show marked irisation similar to that of mother-of-pearl; the most brilliant colours are observed when the sun is several degrees below the horizon. The physical constitution of nacreous clouds is still unknown; it has been suggested that these clouds may consist of minute water droplets or spherical ice particles. Nacreous clouds are rare. They have been observed mainly in Scotland and Scandinavia, but have also been reported from France and Alaska. Measurements have indicated that the nacreous clouds observed over southern Norway occured at an altitude between 21 and 30 kilometers (70,000 and 100,000 feet)."