Brief history of the microscope. The microscope was invented by the Dutch spectacle maker Zaccharias Janssen around 1590. This was the time when Toyotomi Hideyoshi was unifying Japan into a single nation.
In 1655, the Englishman Robert Hooke produced a "compound microscope" that included an objective lens and an eyepiece lens. In 1665, he published Micrographia, the first book describing observations of a variety of organisms made through his microscope. In this book, Hooke named the numerous compartments partitioned by walls as "cells." The discovery of cells triggered the microscope's rapid advancement.
Antonie van Leeuwenhoek of Holland made his own simple microscopes using a single lens, which lead to his discovery of red blood cells in 1673, as well as the discovery of bacteria and human sperm.
Efforts to improve the microscope were made primarily in England in the 18th and 19th centuries. Microscopes developed by Leitz and Zeiss, both German companies, became popular in the last half of the 19th century and onward.

Features. Today there are dozens of microscope manufacturers around the world, making microscopes for education, research and industrial. All microscopes used today for gemological purposes are intended for general industrial use. So, selecting the proper optics for your gemological microscope that will last for long time is a matter of knowledge and expert advice.

The most suitable microscopes for gemological applications are the stereoscopic type allowing details in gems to be viewed in three dimensions. Stereo microscopes for gemological use are usually of low magnification (up to 50X), preferably equipped with continuous zoom magnification system. Step zoom magnification also available from several microscope manufacturers, but the desired 10X magnification is not always available. Zoom ratio and objective lens varied according to the optical design. The old Greenough 12° optical system is one the best.

For the glass wearers is of paramount importance to select eyepieces with high relief to facilitate easy observation. Also, individually adjustable diopter eye-tubes are recommended. Eyepieces having field of view 23 mm at 10X and depth of field around 4.00mm at 64X are highly desirable because the inclusions in the gems are easier observed. Another desirable feature is the adjustable interpupillary distance between the observer's eyes, usually 55 to 75 mm.

Long working distance is an important factor allowing easier manipulation of the gemstone, while observed under the microscope. Preferable working distance should be over 90mm.

Optic manufacturers. The prospective buyer should know what optical components are available in the market and select the most suitable for gemological applications. Gemological microscope fabricators do not make microscope pods, eyepieces and stands; they buy them from various sources, often with their logo, fit them in the microscope base they fabricate and selling them in the open market. Other gemological microscope marketers buy microscopes from various Chinese makers and then alter their appearance by replacing cover parts and adding their logo aiming to confuse the prospective buyer and preventing direct comparison with their competitors. Yet, other microscope marketers avoid to explain the technical specifications and features to prospective customers while pushing their own wares.

Certain microscope pod models from the Leica conglomerate (Zeiss, Wild, etc.) are on the top of the list, followed by some models of Nikon, Olympus and other Japanese manufacturers. At the bottom of the list include all the Chinese manufacturers producing "new" models or making copies of Bausch & Lomb, Nikon and other famous brand names. Others market their microscopes as "Olympus like", but these microscopes are not made in Japan, but in China. Extra caution should be exercised on certain microscope marketers who are selling Chinese copies of Leica microscopes. However, certain models made the Chinese manufacturers meet the minimum requirements for gemological use, but the majority are not acceptable for professional gemological applications due to their low quality. All Russian made microscopes marketed under the names Mikon, Lomo, Geck and MBS are of low quality, not recommended for professional gemological microscopes.

The bottom line. Until recently, Gemlab used the genuine (not copy) Leica optical pod (Model S6E) with 16X wide field eyepieces giving total zoom range from 10X to 64X, pod inclination angle (38o), long working distance (110mm). Moreover, Leica provides a 5-year warranty. However, the marketing practices imposed to the dealers by Leica and the high price do not justify the type of microscope used in gemological applications. At this this time, Gemlab uses the highest quality Chinese-made optical pods in the market, for the budget-cautious buyer.

Answering a common question: What is a digital gemological microscope? Some microscope salesmen point to the numeric digital LCD readout fixed in the gemological base showing the percentage of light intensity. It has nothing to do with the truth digital microscope. It is just a marketing trick addressed to naive and uninformed prospective buyer.