Certificate Transparency in Chrome

This page describes how to observe Chrome's CT state for a secure site. The simplest way is to use the "Security" panel in Chrome's Developer Tools:
Chrome DevTools showing Certificate Transparency status

Detailed Signed Certificate Timestamp information

The exact Signed Certificate Timestamps Chrome sees and their validation status is available through Chrome's NetLog, accessible via chrome://net-internals.
The chrome NetLog should be opened before visiting a website. Then switch to the Events view from the drop-down and look for a 'SOCKET' event type.
Past the certificate chain, the SCTs received, their origin and validation status will show: