Previous studies of Ba10(MnO4)(PO4)5Cl2 had reported a dark turquoise colour, and a similar colour was observed for our sample . A similar dark turquoise colour was observed for the Sr doped samples, with the exception of Ba6Sr4(MnO4)(PO4)5Cl2, where a clearer blue hue was observed (figure ). This particular sample has complete ordering of Sr/Ba in the A1/A2 sites, and thus highlights a key influence of cation ordering on the colour of the pigment. In this respect, computer modelling studies of the influence of the doping strategy/cation ordering on the electronic structure would be of interest for the compositions around this "sweet spot". To characterise the colour of Ba10-xSrx(MnO4)(PO4)5Cl2 solid solutions, the colour coordinates were measured (Figure ). The results show that the a* and b* values are fairly consistent across the series except for Ba6Sr4(MnO4)(PO4)5Cl2, where a* increased and b* decreased compared to the other compositions within the series. These changes are consistent with the colour reflected in Ba6Sr4(MnO4)(PO4)5Cl2 being bluer and less green, hence a more vivid overall blue colour is observed for this sample. Thus, the work has shown the production of a new blue pigment for this cation ordered composition, Ba6Sr4(MnO4)(PO4)5Cl2, which is a significantly cheaper material to prepare than the previously reported YIn1-xMnxO3 series (associated with the high cost of indium). Therefore, this particular composition, Ba6Sr4(MnO4)(PO4)5Cl2 warrants further study for industrial applications. In this respect, a larger batch (≈40g) has been synthesised to show scalability of this material for potential industrial use applications with a similar colour being retained as in the smaller synthesis batch.