Which statement best describes modern silica coatings on diamonds?

• A. They are fairly durable but not permanent.
• B. They are permanent and durable.
• C. They fade quickly under light exposure.
• D. They cannot be applied to diamond surfaces.

Answer: (D)

Silica coatings on diamonds are thin surface layers applied to change or enhance appearance, such as masking certain features or altering optical properties. These coatings are not permanent; they are designed to be relatively stable for normal wear but can be damaged or removed by heat, aggressive cleaning, or abrasion over time. Because coatings can be applied to diamond surfaces, the statement that they cannot be applied isn’t accurate. Therefore, the best description is that they are fairly durable but not permanent.