The Mystery of Grading Natural Stone Slabs
Torin Dixon
Special Correspondent

As a fabricator, how do you know if the slab you are buying is "First Choice," "Standard," or "Commercial" grade? Unfortunately there is a lot of conFusion, and in some cases, outright deception in the grading of stone slabs.

Most fabricators rely on your local distributors to provide you with quality slabs and accurate labeling. Sadly, many distributors don't have an accurate system of disclosing their grading, and in some cases rely on a middleman who either passes off inferior slabs as "First Choice" when likely they are "Commercial" grade. Of course there are many distributors who are honest and ethical, and when asked, will give you an accurate grading description of the slabs in question. But how do you know?

Even though we have national organizations like the Marble Institute of America (MIA) and the Building Stone Institute (BSI) that create all sorts of specifications and technical data, we don't have a "Pedigree" system or clearing house where all imports get graded into the respective classes like dog owners have through the AKC (American Kennel Club). There, specific dog breeds have very defined "breed standards" where all dogs in that class are gauged and determined if they meet the "Standard."

Unfortunately, (fortunately for unscrupulous dealers) each distributor is left to classify and grade stone (or not classify at all) as their own particular interest dictates. So, let me give you some basic guidelines to fairly judge the various types of stone.

Before I get into some general descriptions of grading standards, I would first like to distinguish between the concept of color and pattern descriptions vs. quality elements.

Often times, most designations of "First Choice," "Standard," or "Commercial" grade usually refer to the purely cosmetic visual aspects of a stone slab. Under this description, a "Commercial" grade slab of Ubatuba can be satisfactorily installed in a kitchen with no loss of quality or integrity, merely the visual character of the slab does not fit the generally recognized standard of the industry.

Comparing the visual and purely decorative aspects of stone grading and the notion of physical qualities that can severely affect the usefulness of a particular stone, the concept of "grading" gets distorted. It is easy to assume that a designation of "Commercial" implies inferior quality. For instance, a "Commercial Quality" slab of Delicatus granite would not be suitable for exterior cladding in a freeze-thaw commercial installation due to the extensive use of resin to fill in voids and fissures. This is a failure waiting to happen. But the same material may be perfectly suitable and durable in an interior kitchen application, yet not adhere to the generally acceptable cosmetic description of "Delicatus."

So to clarify, we have purely visual and decorative standards, and we have physical and performance-based standards. These two standards are often in conflict with each other and often misunderstood and/or misapplied.

Visual and Decorative Designations

Many colors of stone have become classics in the United States and have clearly defined "visual standards," if you will. For instance, Ubatuba (Verde Labrador) is widely known in most of the world as a Brazilian green speckled color with deep green color, some black and at times some gold flecks in it. This type of speckled stone is judged to be "First Choice" when the colors fit the "general standard" (of course color is very subjective and one of the most difficult things to describe in life. Green has many variants). The general "Standard" is dark green with no veining whatsoever, and no dark or light spots, while also having complete balance of color and uniform crystal size.

If a slab or bundles of Ubatuba have a black or light spot in it larger than the predominant crystal size and structure, and you can cut around the spot and still get two countertop rips out of the full slab, the general consensus on grading would be to call this "Standard Grade."

If there are many spots and or veins and you cannot get one countertop rip out of the entire slab that fits the defined standard, then the grading would be called "Commercial Grade." The same type of standard would be applied to homogenous type stones like Baltic Brown, Black Galaxy, Blue and Emerald Pearl, and many others of this type.

When it comes to "Exotics," we have greater difficulty defining a "First Choice" Standard, although there are some exceptions. First, a primer on stone names.

Often when a quarrier or prospector finds a new stone color, does the testing, and is ready to bring the new color to market, the owner may choose a name purely for personal or vanity reasons. For instance, I know of a quarry operator who owned a quarry of a Santa Cecilialooking stone, but it was very dark, had veins and would never fit the standard definition of "Santa Cecilia." He named it Santa Rita, after his mother, Rita. The granite name "Santa Cecilia" was named after Saint Cecilia, the patron saint of musicians. Possibly, the original owner of that quarry was likely a musician, or patron of music, or his mother was named Cecilia. You get the point.

Other times a new quarry is similar in color and tone to an established color, or even a color that has been discontinued. The new quarry operator will add the designation "New" as in New Caledonia. And yet there are other stone colors that have absolutely no relation to a persons name, or a similar stone color and is seemingly pulled out of nowhere like the granite name Sedna (Vulcan Gold). Sedna is the sinister sea goddess of Eskimo mythology, or a planetoid of rock and ice about three-quarters the size of Pluto. You choose.

For Exotics, it is a bit harder to define a "Breed Standard" because usually the original quarrier sets the "Standard" by introducing a new color to market based on the characteristics of the first several blocks that are sold. If the color is successful and sought after, this new color (no matter what it looks like) becomes the "Standard."

Are you confused yet? To complicate things further, if a new color becomes widely popular, there are times where the original owner sells a share of a quarry to a partner (for cash flow or ROI purposes) and the new partner may choose to honor the original "Standard" or go ahead and sell the less favorable blocks to other producers who then capitalize on the original name (like Crema Bordeaux) and sell "Standard" or inferior grade slabs as "First Choice," but they may be far from the original designated standard.

This dynamic creates quite a dilemma for many importers and distributors. If they do not know the history of a particular stone name or the quarry, or are buying from a secondary broker, they may not necessarily know exactly how to grade the stone. Generally, if an importer is buying directly from the original source, they are certain to have the proper designation of "First Choice" or "Standard" as the original producer has a vested interest in protecting and maintaining the original quality standards.

At times, an importer may come across an exceptional batch of a particular color and need to distinguish it from the "First Choice" by calling it "Select," "Premier," or some other superlative name. This type of designation is rare and is judiciously applied to only the cream of the crop.

In general, it is best to know both what you are buying and who you are buying from to consistently get the best quality. If you are unfamiliar with a particular stone name, do an internet search and see what you can find to come up with a consensus of what is generally being presented in the marketplace. You will also likely come across the original factory and be able to cross reference the images they provide to the slabs you are interested in buying. However, as stone is from nature, there may be quite a variation in colors presented on the internet, particularly from the class of stones considered "Exotics."

Develop a relationship with a quality importer who consistently offers quality stone, and do not be afraid to ask questions about a color you are considering. If you need to, ask to talk to the buyer to learn about how they grade their stone slabs. If your distributor offers a few bundles as "Standard," then you can bet that the others are "First Quality" and they have the integrity to declare the lesser visual grade as "Standard." Once in a while and importer will receive a bundle in that is clearly inferior and will list it as "Commercial" and the price should reflect a 20% discount as well.

Until there is a better system of uniform grading in natural stone, you will need to be a little more discriminating to make sure you are getting what you pay for. If you receive slabs of Tan Brown that have baseball-sized black spots all over it, know that you have "Commercial" grade slabs and not "First Choice." Armed with basic knowledge, you can save money and also look out for unscrupulous suppliers.

Regarding the issue of "Physical Qualities" and "Suitable Use," this will be the topic of another article. This is an area where a knowledgeable fabricator can prevent a train wreck from happening in the first place with the proper knowledge of stone and the appropriate usage for specific types.

Torin Dixon is an importer/distributor of natural stone slabs and a fabricator/installer since 1977.

Top: Santa Cecilia "First Choice." Bottom: Santa Cecilia "Standard." Top: Verde Ubatuba "First Choice." Bottom: Ubatuba "Standard."

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