When considering designs for engraving on slate coasters, simple and bold graphics tend to work best. This includes designs with strong lines and contrasting elements, as detailed or intricate patterns may not translate well on the textured surface of slate. Here are some effective design types:

• Outlined Shapes: Clean, outlined designs such as geometric patterns or silhouettes are easily readable and leave a lasting impact.
• Text & Fonts: Choose large, bold fonts for names, quotes, or monograms. Serif and sans-serif typefaces that are thick will facilitate easier engraving.
• Nature Themes: Simple designs that incorporate elements like leaves, trees, or mountains can create a rustic charm.
• Symbols & Icons: Consider using recognizable icons (like coffee cups for a cafe) that can be easily engraved without losing detail.
• Minimalist Designs: Less is often more; minimalist and negative space designs have a modern appeal while ensuring clarity.

Ultimately, contrast is crucial—using designs that have a strong difference in color will help the engraving stand out against the natural dark hues of the slate.