Ratnapura is generally safe for solo female travelers. Like anywhere, it's crucial to stay alert and keep personal belongings secure. The local people are friendly and often willing to assist tourists. However, as it is rich with gem mines, it is advised to remain cautious of potential scams related to gem trading. It's also advisable to respect local traditions and dress modestly, especially when visiting religious sites. Public transportation is usually safe but might get crowded at times; hiring a trusted guide or using a taxi can be a better alternative. Of course, always ensure your accommodation is in a safe area.