Grading Tiffany Stone
Because tiffany stone samples vary so greatly, grading it is necessarily a somewhat subjective process, especially where colors are concerned. The following guidelines have been proposed to provide some consistency in assessing the quality of rough and finished tiffany stone.
To apply this grading system, assume you have a Premium Grade stone, then examine it for each quality factor. If any factor does not meet the standard for Premium, assume the stone is High Grade and repeat. If any factor still does not meet the standard for High Grade, then you are grading a Standard Grade stone. In other words, tiffany stone is graded as the highest grade where the stone meets ALL standards for the grade.
You may notice that, using this grading system, it is entirely possible to cut a premium cabochon from standard grade rough, or to cut a standard cab from premium rough. The grade of a rough slab can be used to indicate the difficulty to be expected in using it to produce a premium cabochon. The grade of a finished tiffany stone gem is primarily an assessment of its attractiveness, and is used to determine its value.
 This premium rock is hard, durable, solid, and beautifully patterned. |
Premium Grade Vibrant colors, dramatic patterns, consistent hardness, good resistance to fracturing or shattering, and no visible cavities or cracks. Breccia, or hairline fissures filled with stone, are not cracks. Premium Grade tiffany stone is certain to cut and polish well, with a minimum of waste. |
 Dramatic contrasts, varied colors and intricate patterning mark this cab as a premium quality stone. |
 This cabochon is nicely patterned, but between the lack of intricacy and the muted colors it can only recieve a High grade. |
High Grade Good to vibrant colors, pleasing to dramatic patterns, consistent hardness, good resistance to fracturing and shattering, may include few small cavities and/or cracks. With planning, High Grade tiffany stone will cut and polish well, with low waste. |
 This rock is hard and nicely patterned, but includes some cavities that will limit cutting choices. |
 This rock is just gorgeous, but it has many soft spots and brittle areas that will make it difficult to cut successfully. It will require careful handling and planning. |
Standard Grade Fair to vibrant colors, indistinct to dramatic patterns, inconsistent to consistent hardness, may have a tendency to flake or spall, and may include many cavities and/or cracks. Standard Grade tiffany stone can be cut successfully, but is not guaranteed to produce pleasing cabochons and may involve significant waste. |
 This cab is pretty enough, but its colors are too uniform and its patterning is muted. |
To apply this grading system, assume you have a Premium Grade stone, then examine it for each quality factor. If any factor does not meet the standard for Premium, assume the stone is High Grade and repeat. If any factor still does not meet the standard for High Grade, then you are grading a Standard Grade stone. In other words, tiffany stone is graded as the highest grade where the stone meets ALL standards for the grade.
You may notice that, using this grading system, it is entirely possible to cut a premium cabochon from standard grade rough, or to cut a standard cab from premium rough. The grade of a rough slab can be used to indicate the difficulty to be expected in using it to produce a premium cabochon. The grade of a finished tiffany stone gem is primarily an assessment of its attractiveness, and is used to determine its value.
