Hung has for years collected original stones that are unique in appearance, origin, age and elements. His stones are mostly sourced from Vietnam, including Khanh Hoa and Binh Dinh provinces, while some of them are foreign.

Although the mystery stone has been in his house for years, Hung only recently became aware of its originality about 10 days ago.

Hung woke up one night, and he noticed that the stone was emitting a strange light. It was a kind of blue light, and the light was brighter in darker areas.

“I thought it was a normal stone like many other stones in my collection until that night, when I saw it it emitting in the light,” Hung said.

According to Hung, the stone weighs six kilos and has a length of 25 cm. However, he cannot recall where or when he found it as he has collected many stones for dozens of years.

Hung has tried to learn more about this kind of stone via the internet and by talking to experts, but the stone and its origin and elements remains a mystery.

Hung has more than 1,000 stones displayed at An Phat Quan, his showroom in Bien Hoa City in Dong Nai province.

Two mineralogy lecturers of the HCM City University of Natural Sciences, Dinh Quang Sang and Pham Tuan Long, both of whom have master’s degrees, have reportedly examined the stones but have not been able to given an explanation about the stone.

Hung said the scientists wanted to cut a part of the stone for laboratory research, but he  refused because he wants to keep it intact.

Hung’s friends and relatives, who are collectors of ornamental trees and precious stones in HCM City as well as Binh Duong and Dong Nai provinces were also surprised at nature of the stone.

However, there are many kinds of stones that emit light in the dark.

An expert from the Saigon Jewelry Company (SJC) said these stone can be created artificially by pressing and thermal calcinations, a technique used in making porcelain products.

“The materials used to make stone contain phosphorescent substances which allow stone to emit light in the darkness,” he said.

However, the stone needs to be heated for a certain period in order for it be phosphorescent