Research

GIA Pearl Research

Pearls - The Queen of Gems

Prized by many cultures throughout history and frequently referred to as “The Queen of Gems,” pearls have long been one of the most sought-after gemstones in both the jewelry industry and the world at large. Their unique appearance and the affordability of cultured pearls in the market have allowed their popularity to grow exponentially over the years.

Produced by many mollusk species mainly from the Bivalvia and Gastropoda classes, pearls are made of calcium carbonate in the form of aragonite or calcite, through biomineralization process similar to their host shells. In addition, they also contain a small amount of organic matrix and have excellent mechanical properties; they are truly unique and considered as the most important organic gemstone throughout human history. For an overview of various types of pearls found in nature and used for culturing practices, please watch the following GIA Knowledge Sessions Webinar:

Fascinating World of Pearls and Shells | GIA Knowledge Sessions Webinar Series (youtube.com)

Akoya Pearl Strands

Pearl Identification: Natural vs. Cultured

Before the creation of the first commercially successful cultured pearls in the early twentieth century, pearls were so rare and expensive that they were reserved almost exclusively for the very rich, the royal families, and the gods. Not surprisingly, as demand for natural pearls increased, supply gradually diminished. A desire to satisfy the passions for these treasured biogenic gems around the world led to the commercial development of cultured pearls.

GIA had a long history of pearl testing that can be traced back to 1930s, when Japanese akoya cultured pearls were successfully commercialized and it became critical for gemological laboratories to be able to separate natural pearls from their cultured counterparts. Many types of mollusk species can produce natural and cultured pearls so thorough gemological characterization of known samples from various localities and origins around the global is an essential part of GIA’s pearl research. Some examples of such studies are shown in the following links.

Beach Pearls

Color Treatments and Processes

Detection of treatments, particularly color modification, has been an important part of pearl identification since the early days of GIA. Pearls can be treated into black or golden colors to imitate the Tahitian and golden South Sea cultured pearls in the market, and the treatment techniques have been improved significantly over time, which now requires gem labs to employ more advanced instruments for treatment detection. In addition, pearls may be subjected to routine processes such as bleaching, maeshori (luster enhancement), and optical brightening that can improve their appearances. GIA has developed novel techniques that can identify these post-harvest treatments and processes applied on pearls. Some studies of such applications are listed below.

Advanced and Unconventional Pearl Testing Techniques

Over the past several decades, pearl testing techniques have developed significantly within gemological laboratories around the world. Currently, a number of advanced instruments are routinely employed for pearl identification at GIA, which include real-time X-ray microradiography, X-ray computed microtomography, UV-Vis spectroscopy, energy-dispersive x-ray fluorescence, laser ablation–inductively coupled plasma–mass spectrometry, Raman spectroscopy, and various photoluminescence and fluorescence spectroscopies. Furthermore, novel and unconventional techniques such as radiocarbon dating and DNA analysis of pearls have also been reported and they can provide useful additional information regarding the origin of pearl samples. Some relevant studies from GIA are listed below.

Learn more here about our advanced research instumentation.

Structural Analysis, Biomineralization and Using Pearls as an Environmental Proxy

In addition to the research work in the area of pearl identification, GIA also collaborates and conducts research of this unique biogenic gem material beyond gemology. Some interesting topics we studied in recent years include investigation of nacre nanostructure by analyzing its structural color pattern, using freshwater pearls as a unique proxy for environmental and temperature changes, and discovery of disordered dolomite inside a natural Cassis pearl.