StableNormal is a method designed to improve the stability and sharpness of surface normal estimation from monocular colored inputs, such as images and videos. Unlike previous diffusion-based approaches that struggle with stochastic inference and costly ensemble steps, StableNormal reduces the variance in the diffusion process, enabling "Stable-and-Sharp" normal estimation without additional ensemble processes. The method employs a coarse-to-fine strategy, starting with a one-step normal estimator (YOSO) to produce a reliable initial guess, followed by a semantic-guided refinement process (SG-DRN) to enhance geometric details. This approach is robust under challenging imaging conditions, including extreme lighting, blurring, and low-quality images, as well as transparent and reflective objects. StableNormal has been evaluated on various datasets and real-world applications, demonstrating superior performance in terms of accuracy and stability compared to other state-of-the-art methods. The method is publicly available, making it accessible for research purposes.StableNormal is a method designed to improve the stability and sharpness of surface normal estimation from monocular colored inputs, such as images and videos. Unlike previous diffusion-based approaches that struggle with stochastic inference and costly ensemble steps, StableNormal reduces the variance in the diffusion process, enabling "Stable-and-Sharp" normal estimation without additional ensemble processes. The method employs a coarse-to-fine strategy, starting with a one-step normal estimator (YOSO) to produce a reliable initial guess, followed by a semantic-guided refinement process (SG-DRN) to enhance geometric details. This approach is robust under challenging imaging conditions, including extreme lighting, blurring, and low-quality images, as well as transparent and reflective objects. StableNormal has been evaluated on various datasets and real-world applications, demonstrating superior performance in terms of accuracy and stability compared to other state-of-the-art methods. The method is publicly available, making it accessible for research purposes.