Impregnated

The caption of each scene in the animation above (the first scene lists its three panel captions), with sources.

1. Scene 1Impregnation (jadeite as the example)

   Before: The starting material here is jadeite that has already been acid-bleached, leaving voids between the grains.

   During: Bleached jadeite is typically impregnated with a polymer to fill the open fractures.

   After: The polymer sits in the minute spaces between the crystal grains and in small fractures.

   Treated zone: here, polymer-filled spaces between grains and small fractures

   Sources

   • Identification of Bleached and Polymer-Impregnated Jadeite, by Emmanuel Fritsch et al. (Gems & Gemology, Fall 1992, Vol. 28, No. 3, pp. 176–187)
   • Gem Trade Lab Notes: Jadeite Jade — Bleached and Impregnated, with Distinctive Surface Features (Gems & Gemology, Winter 1994, Vol. 30, No. 4, pp. 266–267)
   • Jade Description
   • LMHC Information Sheet #11, Version 5, May 2025

2. Scene 2Process conditions

   Bleached jadeite is typically impregnated with a polymer to fill the open fractures. In most cases a resin is injected into the piece, reportedly under pressure, and occasionally only wax is used. In one author's experience a vacuum pump is sometimes used first to pull gas bubbles out of the fractures, and the stones may be warmed in a microwave oven to help the injection; afterwards the stones are wiped clean of residual polymer. Some treaters dye the stone before impregnation or mix a dye into the impregnating material, which is a different treatment (dyed and impregnated). The 1992 study believed an Opticon-like resin was probably the one most commonly used.

   Sources

   • Identification of Bleached and Polymer-Impregnated Jadeite, by Emmanuel Fritsch et al. (Gems & Gemology, Fall 1992, Vol. 28, No. 3, pp. 176–187)
   • LMHC Information Sheet #11, Version 5, May 2025

3. Scene 3How it works

   The polymer fills the voids left by bleaching and improves the stone's clarity of appearance. Its refractive index is close to jadeite's (many polymers fall in the 1.55–1.65 range), so the grain boundaries and fractures become less prominent, though they may still be seen with a microscope. Impregnation also stabilizes the bleached stone, but it does not restore the original toughness.

   Sources

   • Identification of Bleached and Polymer-Impregnated Jadeite, by Emmanuel Fritsch et al. (Gems & Gemology, Fall 1992, Vol. 28, No. 3, pp. 176–187)
   • Gem Trade Lab Notes: Jadeite Jade — Bleached and Impregnated, with Distinctive Surface Features (Gems & Gemology, Winter 1994, Vol. 30, No. 4, pp. 266–267)

4. Scene 4After treatment and how it is detected

   The polymer sits in the minute spaces between the crystal grains and in small fractures. In the study, a drop of hydrochloric acid on untreated jadeite spreads through these spaces by capillary action and 'sweats' on the surrounding surface; on impregnated jadeite it does not, because the polymer has filled them. On the surface, the resin is usually found only at the openings of voids or fractures, not as a uniform coating.

   The 1992 study found infrared spectroscopy to be the only method giving conclusive proof of polymer impregnation in all cases: every bleached and impregnated sample studied showed strong absorption around 2900 cm⁻¹ with accompanying features, but the band shape depended on the impregnant — the two wax-impregnated samples were dominated by wax bands at about 2920 cm⁻¹ and 2850 cm⁻¹, the other nine polymer-impregnated samples showed three sharp peaks at about 2965 cm⁻¹, 2930 cm⁻¹ and 2875 cm⁻¹, and yet other material gave a different spectrum. Virtually all jadeite is waxed before it reaches the market, and untreated samples also show wax bands at about 2920 cm⁻¹ and 2850 cm⁻¹, so the whole spectrum has to be read to tell wax from polymer; the laboratories' joint reporting standard (LMHC, 2025 edition) also lists FTIR and Raman spectroscopy. With magnification and reflected light, the surface of some 'B jade' shows the outlines of individual grains, and filler can be seen in some surface-reaching fractures; the studied samples had low specific gravity and mostly fluoresced to long-wave ultraviolet, but neither is conclusive on its own.

   Sources

   • Identification of Bleached and Polymer-Impregnated Jadeite, by Emmanuel Fritsch et al. (Gems & Gemology, Fall 1992, Vol. 28, No. 3, pp. 176–187)
   • Gem Trade Lab Notes: Jadeite Jade — Bleached and Impregnated, with Distinctive Surface Features (Gems & Gemology, Winter 1994, Vol. 30, No. 4, pp. 266–267)
   • LMHC Information Sheet #11, Version 5, May 2025