Lanh My A, a traditional Vietnamese silk fabric, is dyed black using extracts from the fruit of Diospyros mollis Griff. It is valued for its aesthetic appeal and rarity. However, the traditional dyeing process is labor-intensive, time-consuming, and highly dependent on weather, as the fabric requires extended sunlight exposure. Some previous studies focused on the extraction process, solvent optimization, or the dyeing and antibacterial properties of Diospyros mollis extracts. However, the use of artificial radiation sources in the black dyeing process of Lanh My A silk has not yet been addressed. This study investigates the photochemical effects responsible for black color formation on silk dyed with Diospyros mollis extract under artificial light. Four radiation sources from Philips lamps, emitting wavelengths from near-infrared to UVC, were employed to simulate sunlight in the dyeing process. Jersey fabric samples (160 g/m2) were impregnated with the fruit extract solution, and blackness was monitored as a function of radiation dose. After 72 h, black coloration under Blacklight Blue (BLB) lamps was comparable to that under natural sunlight. These findings suggest a follow-up research direction on a viable alternative to sunlight: using artificial UVA sources from BLB fluorescent lamps for large-scale dyeing of Lanh My A. This approach allows better process control, consistent results, and weather-independent production. It also supports the industrialization of this traditional craft, aiming to improve efficiency, scalability, and long-term economic sustainability.