A UV-Vis radiation curable security ink for producing a security feature exhibiting a blue color upon viewing in transmitted light and a metallic yellow color upon viewing in incident light, wherein said ink comprises: a) from 7.5 wt-% to 20 wt-% of silver nanoplatelets having a mean diameter in the range of 50 to 150 nm with a standard deviation of less than 60%, a mean thickness in the range of 5 to 30 nm with a standard deviation of less than 50%, and a mean aspect ratio higher than 2.0, wherein the mean diameter is determined by transmission electron microscopy and the mean thickness is determined by transmission electron microscopy, and wherein the silver nanoplatelets bear a surface stabilizing agent of general formula wherein the residue R A is a C 2 -C 4 alkyl group substituted with a hydroxy group; the residue R B is selected from a C 1 -C 4 alkyl group, and a C 2 -C 4 alkyl group substituted with a hydroxy group; and Cat + is a cation selected from the group consisting of Na +, K +, Cs + and Rb +; b) a perfluoropolyether surfactant functionalized with at least a hydroxy group; c) from about 3 wt-% to about 12 wt-% of a polyvinyl chloride copolymer containing at least 69 wt-% of vinyl chloride; d) d1) from about 25 wt-% to 55 wt-% of a cycloaliphatic epoxide, and from 1 wt-% to 10 wt-% of a cationic photoinitiator; or d2) from 30 wt-% to 65 wt-% of a mixture of a cycloaliphatic epoxide and a radically curable compound, from about 1 wt-% to 6 wt-% of a cationic photoinitiator, and from 1 wt-% to 6 wt-% of a free radical photoinitiator; and optionally e) a cationically curable compound selected from the group consisting of: e1) a vinyl ether having two vinyloxy residues in an amount lower than 50% of the weight percent (wt-%) of the cycloaliphatic epoxide of d); e2) a vinyl ether having one vinyloxy residue in an amount lower than 5 wt-%; e3) an epoxide other than a cycloaliphatic epoxide in an amount lower than 10 wt-%; e4) an oxetane having two oxetanyl residues in an amount lower than 20 wt-%; e5) an oxetane having one oxetanyl residue in an amount lower than 3.5 wt-%; and e6) a mixture of e1) and/or e2) and/or e3) and/or e4) and/or e5); the weight percents being based on the total weight of the UV-Vis radiation curable security ink. a) from 7.5 wt-% to 20 wt-% of silver nanoplatelets having a mean diameter in the range of 50 to 150 nm with a standard deviation of less than 60%, a mean thickness in the range of 5 to 30 nm with a standard deviation of less than 50%, and a mean aspect ratio higher than 2.0, wherein the mean diameter is determined by transmission electron microscopy and the mean thickness is determined by transmission electron microscopy, and wherein the silver nanoplatelets bear a surface stabilizing agent of general formula wherein the residue R A is a C 2 -C 4 alkyl group substituted with a hydroxy group; the residue R B is selected from a C 1 -C 4 alkyl group, and a C 2 -C 4 alkyl group substituted with a hydroxy group; and Cat + is a cation selected from the group consisting of Na +, K +, Cs + and Rb +; the residue R A is a C 2 -C 4 alkyl group substituted with a hydroxy group; the residue R B is selected from a C 1 -C 4 alkyl group, and a C 2 -C 4 alkyl group substituted with a hydroxy group; and Cat + is a cation selected from the group consisting of Na +, K +, Cs + and Rb +; b) a perfluoropolyether surfactant functionalized with at least a hydroxy group; c) from about 3 wt-% to about 12 wt-% of a polyvinyl chloride copolymer containing at least 69 wt-% of vinyl chloride; d) d1) from about 25 wt-% to 55 wt-% of a cycloaliphatic epoxide, and from 1 wt-% to 10 wt-% of a cationic photoinitiator; or d2) from 30 wt-% to 65 wt-% of a mixture of a cycloaliphatic epoxide and a radically curable compound, from about 1 wt-% to 6 wt-% of a cationic photoinitiator, and from 1 wt-% to 6 wt-% of a free radical photoinitiator; and optionally d1) from about 25 wt-% to 55 wt-% of a cycloaliphatic epoxide, and from 1 wt-% to 10 wt-% of a cationic photoinitiator; or d2) from 30 wt-% to 65 wt-% of a mixture of a cycloaliphatic epoxide and a radically curable compound, from about 1 wt-% to 6 wt-% of a cationic photoinitiator, and from 1 wt-% to 6 wt-% of a free radical photoinitiator; and optionally e) a cationically curable compound selected from the group consisting of: e1) a vinyl ether having two vinyloxy residues in an amount lower than 50% of the weight percent (wt-%) of the cycloaliphatic epoxide of d); e2) a vinyl ether having one vinyloxy residue in an amount lower than 5 wt-%; e3) an epoxide other than a cycloaliphatic epoxide in an amount lower than 10 wt-%; e4) an oxetane having two oxetanyl residues in an amount lower than 20 wt-%; e5) an oxetane having one oxetanyl residue in an amount lower than 3.5 wt-%; and e6) a mixture of e1) and/or e2) and/or e3) and/or e4) and/or e5); the weight percents being based on the total weight of the UV-Vis radiation curable security ink. e1) a vinyl ether having two vinyloxy residues in an amount lower than 50% of the weight percent (wt-%) of the cycloaliphatic epoxide of d); e2) a vinyl ether having one vinyloxy residue in an amount lower than 5 wt-%; e3) an epoxide other than a cycloaliphatic epoxide in an amount lower than 10 wt-%; e4) an oxetane having two oxetanyl residues in an amount lower than 20 wt-%; e5) an oxetane having one oxetanyl residue in an amount lower than 3.5 wt-%; and e6) a mixture of e1) and/or e2) and/or e3) and/or e4) and/or e5);