Black Granite Stains

Malicious Stone Doctoring

Do you have black granite stains, ghost marks or white rings? Should black granite change over time? Below is a quick Q&A on the possible causes and solutions.

What Is Malicious Stone Doctoring?
Temporarily altering the look of the stone without telling you. Making a gray stone black. Taking a black stone with a few imperfections or color variations and dying it a solid black.

Black Granite Stains

Why Are Stones Doctored?
Sometimes stones are maliciously doctored to obtain a higher price. Sometimes they are doctored to make them look like a more expensive stone but are sold for less.

Altering the color of a stone without telling you is most common with the black granites. The blacker the stone the higher the price.

How Is It Done?
An industrial oil or a shiny black wax is applied to the surface of a gray stone to make it appear blacker or darker. On other stones, a topical paint might be applied to change the color of the stone.

What Happens?
Over time the doctoring agent wears off leaving rings or marks lighter than your stone.
These marks or rings look like black granite stains.

How Do I Know If A Stone Has Been Maliciously Doctored?
Test The Stone Before Buying It:

Resined Slab

  1. Try the Lemon Juice Test.
  2. Wet the unpolished side of the stone. What color is it?
  3. Look at the edge of the slab before it is fabricated. The edges of a doctored stone will look like a varnish was carelessly applied.

    NOTE: The edges of a resined stone also look like this. Resining is a good thing but MOST high quality black granites are not resined.

After Installation:
Remember that a true stain is always darker than the stained material. A true stain is NEVER lighter than material that is supposedly stained. If the area in question is lighter than the rest of the stone it is either:

  • Surface Damage - Etching. Your stone is sensitive to acids.
  • Doctored - Your stone is dyed.

Does Granite Etch?
MOST granites do not etch but some do!

How Can I Tell If My Stone's Been Doctored Or If It's Etched?
Look at the gloss of the stone where the MYSTERY MARK is. Still shiny? Etches are dull.

What If My Stone Is Doctored?

  1. If you were unaware of the doctoring and you paid for a different stone than was installed, have the fabricator replace it with the correct stone. OR,

  2. Remove all of the doctoring agent and live with the color.

How Do I Avoid Buying A Doctored Stone? Lemon Juice Test

  • Test the slab you plan to buy. Lemon Juice Test.
  • Have the fabricator put in writing that the stone has no artificial colors or temporary dyes applied.

Will My Fabricator Knowingly Install A Dyed Stone?
MOST fabricators will not knowingly install a dyed stone.

"If doctoring produces a permanent result and it's disclosed to you, there’s nothing wrong with it.
If the doctoring produces a temporary result and you are unaware of it, that is deceptive".

Maurizio Bertoli


You'll find More hints & tips on:

Care For Granite Black Granite Stains Etched Marble Black Granite

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