A fast and stable implementation of the CLIME estimator for sparse precision matrices proposed in Cai, Liu, and Luo (2011) can be obtained by using the flare package developed by Xingguo Li, Tuo Zhao, Lie Wang, Xiaoming Yuan and Han Liu. The R package is available here.
The original implementation of CLIME is this
R package, together with the CLIME manual.
Please see the paper Cai, Liu, and Luo (2011) for details of the method.