Emerald is, as of today, formally accepted into the Linden Lab Third Party Viewer directory. According to Linden Lab:-
“The Third-Party Viewer Directory
To be listed in the Viewer Directory, a software developer must self-certify that it complies with Linden Lab policies. Beware of third-party viewers that are not in the Viewer Directory – they have either declined to self-certify or been refused for noncompliance with our policies”
So, use the Emerald Viewer with absolute confidence.
More info here
Modular Systems here
Download Compliant 3rd party Emerald viewer here