A planar optically variable element comprising: a plurality of first optical sub-elements, the optical properties of the first optical sub-elements being configured to cooperate to form a three-dimensional image when light is incident thereon; wherein: the three-dimensional image is a three-dimensional image of an arrangement of facets; the first optical sub-elements are arranged in a two-dimensional polygonal grid, wherein each of the first optical sub-elements has a boundary corresponding to a projection of a boundary between facets of the three-dimensional image such that each first optical sub-element corresponds to a respective facet of the arrangement of facets in the three-dimensional image; each of the first optical sub-elements has at least one dimension of at least 0.1mm; the first optical sub-elements are comprised of a micro-structure of at least one of: a reflection diffraction grating; a transmission diffraction grating; a micro-prism; and a micro-mirror; the planar optically variable element further comprises second optical sub-elements, the optical properties of the second optical sub-elements being configured to provide an image; the second optical sub-elements are elongate; and the second optical sub-elements overlaid over selected boundaries between the first optical sub-elements. a plurality of first optical sub-elements, the optical properties of the first optical sub-elements being configured to cooperate to form a three-dimensional image when light is incident thereon; wherein: the three-dimensional image is a three-dimensional image of an arrangement of facets; the first optical sub-elements are arranged in a two-dimensional polygonal grid, wherein each of the first optical sub-elements has a boundary corresponding to a projection of a boundary between facets of the three-dimensional image such that each first optical sub-element corresponds to a respective facet of the arrangement of facets in the three-dimensional image; each of the first optical sub-elements has at least one dimension of at least 0.1mm; the first optical sub-elements are comprised of a micro-structure of at least one of: a reflection diffraction grating; a transmission diffraction grating; a micro-prism; and a micro-mirror; the planar optically variable element further comprises second optical sub-elements, the optical properties of the second optical sub-elements being configured to provide an image; the second optical sub-elements are elongate; and the second optical sub-elements overlaid over selected boundaries between the first optical sub-elements. the three-dimensional image is a three-dimensional image of an arrangement of facets; the first optical sub-elements are arranged in a two-dimensional polygonal grid, wherein each of the first optical sub-elements has a boundary corresponding to a projection of a boundary between facets of the three-dimensional image such that each first optical sub-element corresponds to a respective facet of the arrangement of facets in the three-dimensional image; each of the first optical sub-elements has at least one dimension of at least 0.1mm; the first optical sub-elements are comprised of a micro-structure of at least one of: a reflection diffraction grating; a transmission diffraction grating; a micro-prism; and a micro-mirror; the planar optically variable element further comprises second optical sub-elements, the optical properties of the second optical sub-elements being configured to provide an image; the second optical sub-elements are elongate; and the second optical sub-elements overlaid over selected boundaries between the first optical sub-elements.