As a consequence of the increasing interest in Collaborative Virtual Environments (CVEs) and the complex nature of such systems, the need for a thorough evaluation framework has become necessary. The current evaluation frameworks suffer from limitations in assessment because they are either confined to evaluation of a specific type of CVE or they focus on a restricted aspect of CVE. This paper presents a framework for THorough Evaluation of COllaborative viRtual Environment (THE CORE). The proposed framework is structured in a four-layered architecture to assure evaluation of the multi-faceted aspects comprising a CVE. The layers evaluate the application usability, tool usability, companion interaction and collaboration outcome. Within each layer, key evaluation tools and factors are provided. In addition, the framework is designed to be generic to be suitable for different types of CVEs. In order to validate the proposed framework, a case study was conducted involving development and evaluation of a 3D CVE. The case study found the four-layered framework to be useful for evaluating both the technical and behavioural aspects of the 3D CVE. As future work, the generality of the framework will be further tested on different types of CVE, potentially leading to modifications and extensions.