The KERN ORA-G series models are universal, maintenance-free analog hand refractometers. Their compact and robust design allows for easy, efficient, and long-lasting use in everyday situations. The manual conversion effort is eliminated by multiple selectable scales, which prevents application errors. These scales are specially developed, precisely calculated, and verified. They are also characterized by very thin and clear lines. The optical system and prism cover are made from special materials that allow for low-tolerance measurements. All models are equipped with an eyepiece that provides easy and smooth adjustment for different vision strengths. The package includes a storage case, calibration solution, possibly a calibration block, a pipette, a screwdriver, and a cleaning cloth. Additional accessories are available separately. This model has a refractive index measurement range for determining gemstones. Additionally, a beautiful leather case is included with this refractometer. The main areas of application are jewelers, the jewelry industry, and education.