What is glass-filling of Diamond Polkies?

Glass filling in diamonds to improve their apparent clarity has been known for a few decades now, where cleavages and fractures of a diamond are filled with a material of high refractive index (closer to that of the diamond).

Commercially, the glass filling of diamonds was first introduced by Zvi Yehuda of Israel in 1980s, which was later performed by many others. Since 2003, similar glass-filling has been applied to low-grade rubies too, which at one point of time, became the most controversial gemstone treatment.

These days, in addition to the regular cut diamonds, glass-filling is being applied to uncut or flat diamonds (polki) too which reduces the visibility of their fractures and improves overall clarity & appearance. It also acts as a sealant, preventing dirt or other foreign substances entering into open cracks of the diamonds.

With unaided eye, a filled diamond may appear slightly greasy with a very slight yellowish overtone; in stones with many treated fractures, the yellowish overtone is more apparent as seen in the above pair of uncut flat diamonds.

As far as durability is concerned, glass filling is usually durable under normal conditions including ultrasonic and steam cleaning. Experiments have shown that the filler can be damaged by boiling in acids & can change colour on overexposure to ultra-violet light. However, kundan meena jewellery is not exposed to such processes, so uncut diamonds are much safer than cut diamonds.

Although, there is nothing inherently wrong with any enhancement process, full disclosure should always be made at every level of sale. However at this stage, such disclosure is being made only by a handful of jewellers while majority of the jewellers-dealers seem to be unaware of the existence of such glass-filled polkis or they are just ignorant. Hence, much of the glass-filled 'polkis' used in kundan-meena jewellery are being sold undisclosed.

We hope that you found this information useful!

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