I have this older looking Velox photograph with the numbers "430" typed on the back. The Velox logo in this photo has an Oval shape around the text with the text being in a fancy sort of font. I have tried looking into this before but to no avail. I did find someone else on here with the same sort of photo with numbers on the back also being in purple and on velox paper, theres was from around 1937 - 1949
It is difficult to date a photo based solely on imprints appearing on the back (non-emulsion) side. The imprints can come from many sources, including the paper manufacturer, processing lab, photographer, retail store, etc. Velox paper was manufactured by different companies, and had different codes at different times relating to contrast and paper finish and weight.
Packets of Kodak Velox printing paper showing the Kodak letter/number system for labeling contrast grade and paper finish.
Velox was originally a Gelatine silver chloride, gaslight development, photographic printing-out paper. It was invented by Leo Baekeland, and manufactured by Nepera Chemical Co., Yonkers, NY, beginning in 1897. In 1899 the company was sold to Eastman Kodak. Velox became a Kodak brand of glossy and matte photo printing papers in various contrast grades. It was marketed as "Velox" until 1947 when they began marketing it as "Kodak Velox".
Prior to 1947 Velox had its own numbering system, after that date Kodak standard designations were used. From c. 1929 the word 'Velox' was surrounded by an oval on the backs of glossy prints, this was to distinguish them when washing and prior to glazing.
Glossy papers had to be glazed on a high-temperature mirror-polished chrome drum in order to achieve the correct finish.
As far as code numbering which appeared on the paper's box or packet, they may or may not have been imprinted on the reverse side. Generally a darkroom technician would not need to know what an individual sheet's contrast grade or paper weight was, since they would have taken it out of a marked box or envelope.
By way of example of coding names, before & after 1947: Bromesko CFL 2 D = Cream Fine Lustre, Normal, Double weight. Pre-1947: 47 Z = Cream Lustre, Medium, Double weight. Bromide WSM 1 S = White Smooth Matt, Soft, Single weight. Pre-1947: BBS 1 = Crayon Black, Soft, Single weight (BBS 1 = Bromide Black Smooth, 1 = soft grade). White Smooth Matt was a completely smooth dead matt paper and Crayon Black was the nearest pre-1947 equivalent surface.
Given these examples of Velox paper's different coding systems, further exploration into the provenance of the photo is not possible without more information or an image of the imprint itself.