Turquoise Grading & Valuation (Part 1)

Turquoise Grading and what’s it worth How to Guide.  (Part One)

Turquoise is an alluring stone that has had much favor for many thousands of years in cultures around the globe due to its beautiful colors and what many have said are spiritual. Whether it was the Native American’s from South America to North America, or the Asian continent’s or the middle east as well as Europe and abroad, and from the ancients to the hippy movement when Jimmy Hendrix and Jim Morrison were adorned in the Gemstone to today Turquoise has been  and will ever continue widely loved and worn. Today we will discuss some ways to grade and compare today's values. Our disclaimer is that grading and assigning a value to turquoise is best done by a turquoise expert or a GIA certified gemologist. The TQI or The Turquoise Quality Index is a good way of examining turquoise to a detailed degree, TQI is an aid in helping to discern value and to compare rarity and quality of the stone examined. Much of the information on TQI is in bits and pieces and the grading numbers takes time to understand and master, none the less it is a valuable exercise in valuing our stones. The hope is that this guide will help you to better understand grading principals and the variances within turquoise. For further study please see the book links and other links below. (Please support Radical Rocks Education efforts and see out links below including Books on Turquoise below. Thanks for helping keep rockhounding alive by simply subscribing to our bog, podcast and YouTube sites)

Color

Color can vary from an Opaque to semi-transparent from a pale almost white-blue to deep dark blue, also green to dark green to a yellowish green. Throughout most of history the robin’s egg blue has been most desirable. The purest Turquoise is hydrous phosphate compound of aluminum and copper that gives this medium blue color that is so well known and loved. Even though the purist form of turquoise is not always the most valuable by today’s standards. Other minerals and compounds cause our Turquoise to enjoy other color variations besides blue. When iron and zink are in the mix the turquoise is called Fausite This gives us the variations of green, some feel green is worth more since it is rarer in nature, however that is not always reflected in its marked values.

 Values from Grading Turquoise Color

Some collectors say blue is the most valuable, some say green and some say the white, and sellers try to influence the market, so it’s best to go with the color your drawn to and then shop. In America the darker colors hold more favor and are in demand more. So, for value it’s not just color but also Intensity and how clear the color is. Some colors in turquoise are just more vivid than others that may be more earthy or waxy and usually fetch a higher market price. Let’s look further into color and perceived values. To reiterate rich vibrant colors are usually more valuable in the market. The Turquoise Quality Index or (TQI) Is a system to value turquoise based on the stones intensity, transition and matrix. The TQI system is a scale 1 to 10 of the rarity of the stones color, the rarer the stones color the higher the number on the scale. Synthetic stones rate a 1 on the scale. Stones that are dyed rate a 2 on the scale. Natural stones need more levels of evaluation, that include the Intensity and the Transition. So, for natural stones the beginning of valuation looks like this; Natural stone = for color 1 then add points for Intensity and transition, as seen below and as we shall discussed further.

Color	Synthetic		Artificially Dyed	Cloudy, Dull, Harsh Transitions		Imperfections, in Color Transitions, Color limited		Dark Colors Smooth Transitions		Vibrant Color, Smooth Color Transitions
1-10	1		2	3-5		6-7		8-9		10

Conclusion; The chart above is based on the charts below “Color Intensity” & “Color Consistency”, they make up a total of 9 point plus 1 point for natural turquoise, for an overall total of maximin 10 points for TQI Grading. Or if simply judging color alone a maximum of 20 points.

Color Intensity

Basically, color intensity is how vibrant and dark the color is as a rule but not always. The exceptions are for the rare white turquoise and a few unique color variations. The rule of thumb for grading stones of more than one color is to go with the lower number on the grading scale.

Pale Stones	Light Colors	Medium Colors	White Stones	Dark Colors	Vibrant/Rich Colors
1	2	3	3	4	5

Conclusion; color intensity scoring range 1-5 points.

Color Consistency

Color consistency is an evaluation on the consistency of the color. If the stone is one solid color with no changing to dark or light or from one color to another color the consistency is Very high on our scale and has low to no transition of color. Please note that this is not about the matrix of the turquoise as this material is not turquoise. If our turquoise is a blue and green stone for example is the transition smooth or is it an abrupt change form blue to green? The more changes and variations of a color the lower the score. Dyed and stabilized stones may suffer and receive lower scores as well. Rule of thumb always use the lowest score when multiple color transitions have occurred.

Obviously Harsh Transitions	Clearly Sharp color, Inconsistent Color Transitions	Minor Transitions Imperfections	Smooth Color Transitions
1	2	3	4

Conclusion; color consistency scoring range 1-4 points.

Matrix of Turquoise

The next category of grading is the matrix. As turquoise was forming in cracks and crevasses it would form on the host rock or stone, this could also at times occur as other minerals and rocks had formed or as they formed, at times these non-turquoise rocks and minerals will be found mixed with in the turquoise as a matrix. A wide range of minerals and rocks are found as a matrix within the mined turquoise as fragments such as sandstone, pyrite, quartz, molybdenum, and others. The matrix can form many shades and patterns. All matrix is different and may add character to the stone, or they may be porous, grainy or cloudy, these imperfections and specs are usually less desirable. The rarer the pattern and the better the consistency of the matrix the better. Turquoise stones made artificially from turquoise powder or chips will never receive higher than a 1 on the grading scale for matrix. Dyed stones never receive higher than a 2 on the matrix scale. Natural stones will have to be examined more for grading the matrix. The scale for natural turquoise is 1 for color plus Matrix plus Consistency. This scale is for Consistency.

Matrix	Synthetic	Dyed	No Pattern, Cloudy Clarity	Common Pattern, Grainy Clarity	Rare Patterns, Good Clarity	Rare Patterns, Perfect Clarity
1 -10	1	2	3-5	6-7	8-9	10

Conclusion; The chart above is based on the chart below for a total of 10 points for TQI grading. Or if simply grading matrix itself for a total of 20 points.

Matrix Pattern

 The rarer the pattern of the matrix the higher the score. The rarity and consistency are both used for scoring and grading. Some rare patterns include Calico, Spider web, water Web, and Micro Web. Calico must have three or more matrix colors that can include combinations of light brown and shades of brown in golden, dark brown, or black matrix and can include metallic Pyrite. The spider web pattern is the most desirable and usually receives the highest market values. Good patterns of spider web, water web, micro web, and megaweb are rare and will score up to a 5 on the scale below, black web is usually most desirable due to its rarity. Synthetic stones always score a 1, artificially engineered stones or turquoise dust or chips will not receive higher than a 2 on the matrix pattern scale. For natural stones it must be examined, and the score is 1 plus Matrix Pattern plus Consistency as stated earlier.

Slight Matrix, or Synthetic	Good solid matrix no pattern, or Engineered	Sparse Pattering & Matrix	Good Matrix, Little Patterning, or with Rare Pattering	No Matrix Pure Turquoise[SRR1] , Calico, Spider Web	Rare, Over Exaggerated Patterns
1	2-3	4-5	6 -7	8-9	10

Matrix conclusion; Scoring is from 1-10 for TQI.

Turquoise Guides

Turquoise (Updated): The World Story of a Fascinating Gemstone

The Allure of Turquoise

Turquoise Mines, Minerals, and Wearable Art, 2nd Edition

The Great American Turquoise Rush: 1890-1910

“Remember Rockhounds don’t Die They petrify”                                                    

Join me on the Radical Rocks Podcast, our Blog or social media below, also see our affiliate links below that help support our mission to keep Rockhounding and lapidary arts alive and thriving. Feel free to contact me with any suggestions on this blog or any other ideas you may have. If you would like to sponsor in some way, or have your club, book, or mine, spotlighted in Radical Rocks, Blog, Podcast or Video’s feel free to contact Shane with Radical Rocks

http://anchor.FM/shane495

https://radicalrocksusa.blogspot.com/

https://twitter.com/RadicalRocksUSA

https://www.linkedin.com/in/shane-ripley-a281768/

https://www.facebook.com/groups/2478386059095174/

https://www.youtube.com/channel/UCBe_Ds0ARJ7nA1TqgucZamw?view_as=public

Affiliate/referral links

Fundrise, become a real estate investor for only $500 I have for months now and it’s been earning an average of 10% dividends. https://fundrise.com/i/33o5g

Reference for more information  https://www.researchgate.net/publication/322465744_Turquoise_Grading_in_Persian_historical_and_modern_times_a_comparative_study

---

 [SRR1]