Security devices

A method of making a security device, comprising:

• (a) providing an at least semi-transparent layer;
• (b) modifying regions of the at least semi-transparent layer to form a first pattern of integral regions having a raised surface relief relative to intervening regions of the layer, the first pattern comprising raised regions each having at least two flank surfaces that are non-parallel to a plane of the device, and the material of the raised regions being of high optical density relative to the material of the intervening regions of the layer;
• and, before, during or after step (b):
• (c) applying a colour layer on one side of the at least semi-transparent layer, the colour layer forming a second pattern of elements of at least two different colours following the contours of the raised surface relief, the second pattern being configured such that (i) at least two of the flank surfaces of each raised region exhibit different colour appearances and (ii) elements of the second pattern corresponding to the intervening regions of the first pattern are semi-transparent;
• wherein the first and second patterns at least partially overlap one another and are configured such that:
• when the device is viewed in reflected light from at least a first side of the device, the first and second patterns co-operate to generate an optically variable effect, whereby the appearance of the device changes between a first colour and a second colour at different viewing angles;
• and
• when the device is viewed on-axis in transmitted light, a colour is exhibited which is different from the colour exhibited by the device when viewed on-axis in reflected light from the first side of the device.