• Teerat Watcharatpong
  • Panot Krongsut
  • Bhuwadol Wanthanachaisaeng


Gemstones, Heat treatment, Microwave, Silicon Carbide, Dielectric, Zircon


This research was developed to reduce cost of gemstone heat treatment, defined as a common process to improve a quality of gemstones, for local gem burners by using an interaction of a dielectric material in a microwave oven which can be applied as alternative method to use instead of an electric and a gases furnace. The objectives of the study were (1) to examine the trend of the relationship between times, temperature, and power (2) to find out the best composition between SiC and heat-transfer mediums. After the result was formulated, a research prototype was created by remodeling the crucibles with SiC and the heat-transfer mediums, then heated the system using the microwave oven. Based on the findings of this investigation it was concluded that temperatures can hit the peak at 840˚C for oxidation and 1000˚C for reduction which is proved by the colour enhancement of zircon. The final model based on this study can be practically used for burn reddish brown zircon (collected from Ratanakiri, Cambodia) to becomes sky blue (reduction) and colorless (oxidation).


Download data is not yet available.


Breeding, C.M., & Shigley, J.E. (2009). The “Type” classification system of diamonds and its importance in gemology. Gems and Gemology, 45(2), 96-111.

Devouard, B., & Notari, F. (2009). Gemstones: From the naked eye to laboratory techniques. Elements, 5, 163-168.

El-razek, A.A., Saed, E.M., & Gergs, M.K. (2014). Effect of grain size on the dielectric properties of

Lanthanum doped PbTiO3 perovskite ceramics. IOSR Journal of Applied Physics, 6(5), 20-29.

Emmett, J.L., Scarratt, K., McClure, S.F., Moses, T., Douthit, T.R., Hughes, R., Novak, S., Shigley, J.E.,

Wang, W., Bordelon, O., & Kane, R.E. (2003). Beryllium diffusion of ruby and sapphire. Gems and Gemology, 39(2), 84-135.

Fritsch, E. & Rossman, G. (1987). An update on color in gems. Part 1: Introduction and colors caused by dispersed metal ions. Gems and Gemology, 23(3), 126-139.

Laithummanoon T., & Wongkokua, W. (2013). Effect of heat treatment on color of natural zircon.

Journal of King Mongkut’s University of Technology North Bangkok, 23(2), 261–269.

Liu, X., Zhang, Z., & Wu, Y. (2010). Absorption Properties of Carbon Black/Silicon Carbide Microwave

Absorbers. Composites Part B-engineering, 42, 326-329.

O'Dwyer, J.J. (1973). The theory of electrical conduction and breakdown in solid dielectrics (2nd ed). Oxford: Clarendon Press.

Raju, G.G. (2003). Dielectrics in Electric Fields. Marcel Dekker Inc. New York. 592p.

Siriaucharanon, W., Lomthong, P., Seneekatima, K., & Wanthanachaisaeng, B. (2016). Heat treatment of zircon from Tanzania and Cambodia. Proceedings of the 5th GIT

International Gem and Jewelry Conference (267-270). Pattaya, Thailand: Gemological Institute of Thailand.

Smith, M.H., & Balmer, W.A. (2009). Gem News International: Zircon mining in Cambodia. Gems and

Gemology, 45(2), 152-153.

Swain, S., Pradhna, S.K., Jeevitha, M., Acharya, P., Debata, M., Dash, T., Nayak, B.B., & Mishra, B.K. (2016). Microwave heat treatment of natural ruby and its characterization. Applied Physics

A: Materials Science and Processing, 122, 1-7.

Thongcham, K., Sahavat, S., & Wongkokua, W. (2010). Effects of annealing to colour of zircon. Proceedings of the 5th International Workshop on Provenance and Properties of Gems and Geo-Materials (111–113). 2010; Hanoi, Vietnam.

Trew, R.J. (1998) SiC for microwave power applications: present status and future trends. Proceedings of the Gallium Arsenide Applications Symposium (181-186). Amsterdam, The Netherlands.

Wanthanachaisaeng, B. (2014). Zircon and Its Heat Treatment, Burapha Science Journal, 19, 160-168.

Zeug, M., Nasdala, L., Wanthanachaisaeng, B., Balmer, W.A., Corfu, F., & Wildner, M. (2018). Blue zircon from Ratanakiri, Cambodia. The Journal of Gemmology, 36(2), 102-122.






บทความวิจัย (Research Article)