RGM-PLUG Professional Gemological Refractometer with Built-In Plug-In Light | 1.31–1.81 RI

Identify and evaluate gemstones with the RGM-PLUG Gemological Refractometer, a portable optical instrument designed for gemology students, jewelry professionals, gemstone collectors, lapidaries, and hobbyists. Featuring an integrated plug-in light source, a durable die-cast aluminum body, and a refractive index measuring range of 1.31–1.81 RI, this instrument offers a practical solution for examining the optical properties of gemstones.

Unlike battery-powered models that may become difficult to read as batteries weaken, the RGM-PLUG uses a corded electrical light source to provide consistent illumination during testing. Its included monochromatic light filter, polarizing filter, gemstone refractive index chart, and English-language instructions help users get started with gemstone identification and optical examination.

Each unit includes a 3.6 mL vial of 1.800 refractive index contact liquid, providing the high-index fluid needed for testing many gemstones with refractive indices above the range of commonly supplied lower-index liquids.

Key Features and Benefits

• Broad refractive index range: Measures refractive indices from 1.31 to 1.81 RI, covering many common gemstones and gemological materials.

• Built-in plug-in illumination: Uses a corded electrical light source rather than replaceable batteries, helping maintain consistent illumination throughout testing.

• Designed for gemstone identification: Helps distinguish between gemstones with different optical properties when used alongside other gemological observations and identification methods.

• Useful for cabochons: Supports refractive index examination of suitable cabochon-cut gemstones, which can be difficult to evaluate using some conventional methods.

• Examine optical behavior: When used with the appropriate filter and technique, the instrument can help users investigate optical characteristics, including evidence of double refraction.

• Durable metal construction: Features a die-cast aluminum housing rather than an all-plastic body.

• High-index contact fluid included: Supplied with 3.6 mL of 1.800 RI liquid to support testing of higher-index gemstones within the instrument's measurement capabilities.

• Accessories included: Comes with a polarizing filter, monochromatic light filter, gemstone RI chart, protective carrying case, and English-language user instructions.

• Beginner-friendly documentation: Includes instructions written in English to help new users understand the instrument and its operation.

• Five-year warranty: Supplied with a stated five-year warranty against defects, subject to the manufacturer's applicable warranty terms.

Product Specifications

What Is a Gemological Refractometer?

A gemological refractometer is an optical testing instrument used to measure the refractive index (RI) of a gemstone. Refractive index describes how light changes direction when it passes between materials with different optical properties.

Because different gemstones exhibit characteristic refractive index values, RI testing is an important part of professional gem identification. A refractometer reading can help narrow down the possible identity of a stone and distinguish materials that may look similar to the naked eye.

The RGM-PLUG provides a measuring range of 1.31–1.81 RI, making it useful for examining a broad selection of gemstones. Refractometer results are most reliable when interpreted alongside other characteristics, such as color, specific gravity, inclusions, birefringence, and other appropriate gemological tests.

Important: A refractometer does not independently prove that a gemstone is natural, synthetic, treated, or imitation. It provides optical data that contributes to a broader identification process.

How Does the RGM-PLUG Work?

The instrument uses an internal glass measuring element, a contact liquid, controlled illumination, and an optical viewing system to display the gemstone's refractive behavior.

The refractive index reading can then be compared with reference information for known gemstones. Correct contact-liquid selection, clean measuring surfaces, proper alignment, and suitable lighting are important for obtaining useful results.

Why Does the Included 1.800 RI Liquid Matter?

The refractive index of the contact liquid affects which gemstones can be tested effectively. If the liquid's refractive index is too low for the gemstone being examined, a suitable boundary may not be visible, making a reliable reading difficult or impossible.

The RGM-PLUG includes 3.6 mL of 1.800 RI contact liquid, an important consideration for users who need to examine higher-index materials. Many lower-index contact liquids are not suitable for every gemstone within this instrument's stated measurement range.

Always follow the liquid manufacturer's handling instructions, compatibility guidance, and safety precautions. Use only a suitable contact liquid and avoid unnecessary exposure to the stone, instrument, skin, and surrounding surfaces.

Who Should Use the RGM-PLUG?

What Is Included with the RGM-PLUG?

Every package is described as including the following items:

• RGM-PLUG gemological refractometer with built-in electrical illumination

• Black vinyl soft carrying case and hard protective case

• Polarizing filter

• Monochromatic light filter

• 3.6 mL vial of 1.800 RI contact liquid

• Gemstone refractive index reference chart

• English-language operating instructions

• Beginner's how-to guide

Please refer to the package description and included accessories when ordering to confirm the current configuration.

Frequently Asked Questions

What is the refractive index range of the RGM-PLUG?

The specified measuring range is 1.31–1.81 RI, allowing examination of many gemstones and other gemological materials within that range.

Does the RGM-PLUG require batteries?

No batteries are required for the built-in light source when the instrument is operated using its supplied 110 V electrical connection. Confirm the power requirements and plug configuration before use.

What is the advantage of a plug-in gemstone refractometer?

A corded light source avoids the gradual dimming associated with weakening batteries. Consistent illumination can make routine testing more convenient, although correct technique and viewing conditions remain important.

Can I use the RGM-PLUG to identify fake gemstones?

It can help distinguish materials with different refractive indices, which is useful in gemstone identification. However, RI alone cannot establish whether a stone is natural, synthetic, treated, or imitation. Other tests may be necessary.

Can the RGM-PLUG test cabochon gemstones?

It can be useful for suitable cabochons. The stone's surface, contact conditions, and optical properties affect whether a reliable reading can be obtained.

What is the purpose of the polarizing filter?

A polarizing filter helps users examine certain optical characteristics and can assist in evaluating double refraction when used with appropriate testing techniques. It is one part of a broader gemological testing process.

Why is 1.800 RI contact liquid included?

The included liquid supports testing of higher-index gemstones for which lower-index liquids may not provide suitable optical contact. It should be used according to its specifications and safety instructions.

Is this refractometer suitable for beginners?

Yes. The supplied English-language instructions, beginner's guide, and gemstone RI chart help users learn the basic procedure. Beginners should practice with known reference stones and use additional identification methods when necessary.

What is the warranty?

The product is advertised with a five-year warranty against defects. Please confirm the applicable warranty terms and coverage with NI Supply before purchase.

Does NI Supply offer assistance with using the instrument?

NI Supply provides product information and customer assistance. Contact us with questions about the instrument, included accessories, or its suitability for your intended application.

Why Buy Your Gemological Refractometer from NI Supply?

At NI Supply, we focus on providing useful testing instruments, practical product information, and customer support to help buyers choose equipment suited to their applications.

The RGM-PLUG combines a broad refractive index range, integrated corded illumination, durable metal construction, and useful starter accessories in one portable package. Its included 1.800 RI liquid and English-language instructions add practical value for both new and experienced users.

Whether you are studying gemology, examining a personal gemstone collection, working with cabochons, or adding an optical testing instrument to a jewelry business, the RGM-PLUG offers a convenient way to investigate gemstone refractive properties.

Order your RGM-PLUG Gemological Refractometer from NI Supply today.

NI Supply — National Industrial Supply

Specialized testing instruments and measurement equipment.

• Website: www.nisupply.com

• Email: nisupply@gmail.com

• Phone: 310-748-6858

• Mailing address: 30777 Rancho California Road, #891420, Temecula, CA 92589, USA

Contact NI Supply for product questions, application guidance, and assistance selecting the appropriate refractometer for your needs.