Input:
\documentclass{beamer}
\usetheme{Boadilla}
\usecolortheme{whale}
\usefonttheme{professionalfonts}
\setbeamertemplate{theorems}[numbered]
\begin{document}
\section{First section}
\begin{frame}
\frametitle{Theorems}
\begin{definition}
Text
\end{definition}
\begin{theorem}
Text
\end{theorem}
\begin{lemma}
Text
\end{lemma}
\begin{theorem}
Text
\end{theorem}
\begin{example}
Text
\end{example}
\end{frame}
\end{document}
Output:
Question: Note that example's blocks are green and all other blocks are blue. How to define a specific color for each kind of block? For example, red for theorems and yellow for definitions. It is important to keep the automatic consecutive numbering.