01
Look beyond the face color
Ask the slater to assess the thickness of the neighboring pieces and the available space in the course. A conspicuous replacement may reflect a profile difference rather than a color problem. Natural stone varies, so a single measurement from one broken corner should not define an entire order. Compare a representative range from sound material where access permits.
02
Let the installer confirm fit
Share the proposed replacement with the person performing the repair before buying a large quantity. Have them consider the piece's shape, fastening approach, and relationship to adjacent slates. Keep a record of the material that fits successfully. For future repairs, that practical reference may be more useful than a generic trade name that has been applied to several different thickness selections.