OC Stone Guide curates; these organizations set the standards. Editions listed are current as of October 2026, and we re-check them each year. ASTM pages are summary and purchase pages; the full standards are sold by ASTM.
Natural Stone Institute (NSI)
The natural stone industry’s trade association, formed in 2018 when the Marble Institute of America and the Building Stone Institute combined.
- About NSI and its history
- For homeowners
- Care & cleaning of natural stone
- Stain removal
- Technical bulletins
- Resource Library, including the Dimension Stone Design Manual (2024)
- Testing frictional properties of natural stone walking surfaces (NSI’s DCOF study and recommendation)
ASTM International: dimension stone specifications
Developed by ASTM Committee C18 on Dimension Stone. Each specification sets material characteristics, physical requirements and sampling for a stone type.
- Marble: ASTM C503/C503M-23, Standard Specification for Marble Dimension Stone
- Limestone: ASTM C568/C568M-22, Standard Specification for Limestone Dimension Stone
- Granite: ASTM C615/C615M-23, Standard Specification for Granite Dimension Stone
- Sandstone, quartzitic sandstone and quartzite: ASTM C616/C616M-22, Standard Specification for Quartz-Based Dimension Stone
- Slate: ASTM C629/C629M-22, Standard Specification for Slate Dimension Stone
- Travertine: ASTM C1527/C1527M-23, Standard Specification for Travertine Dimension Stone
- Selecting stone: ASTM C1528/C1528M-26, Standard Guide for Selection of Dimension Stone
- Exterior stone paving: ASTM C1950/C1950M-25, Standard Guide for Selection, Design, and Installation of Exterior Dimension Stone Paving Systems
- ASTM’s current list of C18 material specifications
Slip testing
- ANSI A326.3-2021, American National Standard Test Method for Measuring Dynamic Coefficient of Friction of Hard Surface Flooring Materials (published free by the Tile Council of North America, the committee secretariat)
- DCOF frequently asked questions (TCNA): explains the 2021 product-use classifications and why a DCOF value doesn’t predict whether someone will slip
- ASTM C1028, the older static-friction test, was withdrawn in 2014. The Natural Stone Institute recommends ANSI A326.3 for natural stone walking surfaces instead.
Hiring and permits in California
- CSLB: home improvement contracts and your right to cancel
- Your city’s building department, or OC Public Works for unincorporated areas (linked from each city guide)
Prices
Cost ranges are compiled from the published sources listed on the 2026 OC cost guide. They are ranges, not quotes.
See also our natural stone disclaimer.