Zoho CRM now has a built-in way to capture a Deal's previous stage, called Stage History, so this no longer needs a custom Deluge workaround for the Deals module specifically.

Stage History on Deals

The Stage field on Deals acts as a default field tracker. Every time a Deal's stage changes, the previous stage, the new stage, the duration spent in the previous stage, and who made the change are automatically recorded and shown as a Stage History related list on the Deal record. Four fields, Expected Revenue, Amount, Probability, and Closing Date, are followed by default in this history, and you can add further fields from the Deals module if you need more context captured alongside each stage change.

Tracking previous values on other picklist fields

The same kind of history tracking, called Picklist History, can be enabled on other picklist fields too, not just Deal Stage. For example, tracking Lead Status shows how long a Lead spent at each status before moving to the next, which is useful for spotting where records stagnate in your process.

1. Open the field's settings. Go to the relevant module's layout, select the picklist field you want to track, and click the More icon.
2. Enable tracking. Choose Edit History Tracking, or the equivalent tracking option, and turn it on for that field.

If you specifically need the current stage's running duration

Stage History naturally shows how long a Deal spent in a stage once it has moved on, but doesn't show a live, running duration for the stage a Deal is currently sitting in. If you need that specifically, for example to flag Deals that have been stuck in Negotiation for too long right now, this still requires a small custom function that reads the Stage History related list via the API and calculates the time since the last stage change.