Figure 1. The GIA 7 Pearl Value Factors system classifies pearls according to size, shape, color, luster, surface, nacre, and matching. Composite photo by GIA staff. Prized by many cultures throughout ...

Rough pink diamonds are rarely found, and although the cause of color has been correlated with plastic deformation, the precise mechanism and atomic configuration for the resulting color are topics of ...

This chart focuses primarily on the types of natural inclusions found in tourmaline, as well as the minerals in which tourmaline can be found as an inclusion. Treatments such as enhancement of ...

CARLSBAD, Calif. – August 26, 2025 – GIA, the Gemological Institute of America, will launch revised evaluation services for D-to-Z laboratory-grown diamonds on October 1. Current GIA laboratory ...

The Karowe Diamond Mine in Botswana, owned and operated by Lucara Diamond Corp., has gained international recognition for producing large, high-quality type IaB or coexistence of IaB with IIa diamonds ...

Raman spectroscopy confirmed the identity of the material as pezzottaite by an intense peak at ~1100 cm –1, which is not present in beryl. Fourier-transform infrared spectroscopy showed features ...

CARLSBAD, Calif. – June 2, 2025 – Beginning later this year, GIA (the Gemological Institute of America) will start using descriptive terms to characterize the quality of laboratory-grown diamonds and ...

Figure 1. Sapphires from Madagascar: a beautiful 3.29 ct untreated faceted stone and an assortment of rough in the background. Madagascar has produced many high-quality stones in the last few years ...

“Rabbit hair” quartz is a commercial variety of quartz with special inclusions. These inclusions resemble rabbit fur and are shorter and thinner than the typical rutile, tourmaline, or other acicular ...

Carved single-crystal diamond rings are rare, with few examples to reference (see Spring 2020 Lab Notes, pp. 132–133). But with advancing technology in the laboratory-grown diamond industry, the ...

Figure 1. Top: These five opal slices of comparable thickness were cut from the same rough. They were semitransparent to translucent when viewed in daylight on a black background. Play-of-color was ...

適切なお手入れをすれば、シトリンは美しくてジュエリーに多彩に用いることのできる宝石である。 – Robert Weldon 宝石や鉱物の硬度はモース硬度スケールで測定されます。 モース硬度の ...