Well the process isn't quite the same, they are missing the immense value-add of substantial human suffering in their creation.
Natural diamonds typically emit blue fluorescence, while some lab-grown diamonds may show stronger, inconsistent, or different colors (e.g., orange, green, or yellow).
After turning off the UV light, observe if the diamond continues to glow (phosphorescence), natural diamonds don't.
Except some famous natural ones, like the Hope Diamond[1] do show phosphorescence.