New Delhi, June 24 -- Diamonds symbolize a lifetime commitment for some and mark important milestones for others. Step into any velvet-lined luxury jewellery showroom, and the experience is carefully crafted to be intoxicating, with the stones marketed as possessing "timeless value".

But step outside the showroom, and the illusion quickly fades. Try monetizing the gem during a financial crunch, and the reality of the secondary market can be sobering. Disruption from lab-grown diamonds, supply pressures and shifting consumer preferences have exposed an uncomfortable truth: they are a sentimental splurge or a consumable luxury-not an investment.

One must look at the cracks in the global diamond market to understand the risk of treating di...