KLEURMETER

The ZVI Yehuda Rough Diamond Colorimeter is a professional instrument designed for fast and consistent colour evaluation of rough diamonds. Available in F-50 and F-1000 models, it predicts diamond colour across the D–K range with approximately ±½ colour grade accuracy and provides a measurement result in approximately 5 seconds. The supplied F-50 documentation confirms the D–K range, ±½ grade accuracy and 5-second measurement time.

Beyond basic colour evaluation, the instrument provides information on fancy yellow colour, blue and yellow fluorescence, brown hue and Type IIa/IIb characteristics, making it a powerful tool for professional rough diamond assessment and purchasing decisions.

The colorimeter can also evaluate suitable coated diamonds and provides a stone signature that can be followed from rough through to polished diamond.

Key Features

• D–K rough diamond colour prediction
  
• Approx. ±½ colour grade accuracy
  
• Fast 5-second measurement
  
• Measures Fancy Yellow colour grades
  
• Fancy results include Light, Fancy, Intense and Vivid Yellow
  
• Detects blue fluorescence
  
• Detects yellow fluorescence, which can indicate cloudiness or milkiness
  
• Detects brown hue within the D–F colour range
  
• Type IIa detection to assist in determining HPHT suitability
  
• Type IIb detection for evaluation of blue diamonds
  
• Measures suitable coated diamonds
  
• Stone signature can be followed from rough to polished
  
• Rechargeable for portable professional use
  
• 110/220V operation
  

Designed for professional diamond dealers, manufacturers and rough diamond specialists
Diamond Colour & Fluorescence Analysis

The colorimeter measures rough diamonds across the D–K colour range and also provides dedicated evaluation for fancy yellow diamonds. The F-50 documentation specifies five fancy-yellow result categories: No Fancy Yellow, Light Fancy Yellow, Fancy Yellow, Intense Yellow and Vivid Yellow.

Blue fluorescence is classified across five levels: None, Faint, Light, Medium and Strong. The instrument also detects yellow fluorescence, which may indicate cloudiness or milkiness within the stone.

Brown hue analysis is provided within the D–F colour range.

The colorimeter provides additional information on Type IIa diamonds, including indications relevant to assessing whether a rough diamond may be suitable for HPHT treatment.

It also provides Type IIb blue/grey diamond results. According to the supplied F-50 documentation, a Type IIb blue result indicates that the stone was not radioactively irradiated to change its colour to blue, although it may alternatively indicate a synthetic stone.

Two Models Available

• ZVI Yehuda F-50
  Model: F-50
  Suitable Rough Diamond Weight: 0.30–50 ct
  Colour Range: D–K
  Weight: Approx. 1.1 kg
  Height: 9 cm
  Width: 8.8 cm
  Length: 15 cm
  
• ZVI Yehuda F-1000
  Model: F-1000
  Suitable Rough Diamond Weight: 0.30–1000 ct
  Colour Range: D–K
  Weight: Approx. 1.3 kg
  Height: 10 cm
  Width: 9.8 cm
  Length: 16 cm

The key difference is capacity: choose the F-50 for rough diamonds from 0.30–50 ct, or the F-1000 for exceptionally large rough stones up to 1000 ct.

Technical Specifications

• Brand / Manufacturer: ZVI Yehuda Ltd.
  
• Product Type: Rough Diamond Colorimeter
  
• Models Available: F-50 / F-1000
  
• Colour Measurement Range: D–K
  
• Colour Accuracy: Approx. ±½ colour grade
  
• Measurement Time: Approx. 5 seconds
  
• Fancy Yellow Evaluation: Yes
  
• Blue Fluorescence Detection: Yes
  
• Yellow Fluorescence Detection: Yes
  
• Brown Hue Detection: D–F colour range
  
• Type IIa Detection: Yes
  
• Type IIb Detection: Yes
  
• Coated Diamond Measurement: Yes, subject to measurement requirements
  
• Power: 110/220V
  
• Power Supply: Rechargeable
  
• Operating Time: Approx. 15–16 hours depending on specification/model
  
• F-50 Capacity: 0.30–50 ct
  
• F-1000 Capacity: 0.30–1000 ct

Note: The supplied F-50 manual specifies approximately 16 hours of operation from a full charge and approximately 5 hours for recharging.

Ideal For: Rough diamond dealers, Diamond manufacturers, Diamond buying offices, Diamond cutters and polishers, Gemmologists, Diamond laboratories, Professional rough diamond evaluation, Diamond colour prediction, Fancy yellow diamond assessment, Type IIa and Type IIb evaluation, Fluorescence and brown hue assessment

Why Choose the ZVI Yehuda Rough Diamond Colorimeter?

The ZVI Yehuda Colorimeter goes beyond conventional colour prediction by combining D–K colour evaluation with fancy yellow analysis, fluorescence detection, brown hue measurement and Type IIa/IIb information.

With results available in approximately 5 seconds, rechargeable operation and two capacities available, it provides a practical professional solution for evaluating rough diamonds before cutting and polishing.