Check out this note:

Did you notice anything uncommon?
Check again:
Noticed the star [*] mark in the number panel? Such notes are called:
*Star Series Notes*
The star series notes look exactly like the existing notes but have an additional character i.e. a * (star) in the number panel between the prefix and serial number.
Here’s what you need to know about these notes:
- In the printing stage of notes, when any defect is detected, such notes are replaced by star series notes.
- That is why these notes are also called replacement notes.
- This is done in compliance with international best practices and to ensure cost effective printing system.
- The issue of star series notes started from year 2006 for notes of denomination 10, 20 and 50.
- From 2009, star series notes started getting printed for notes of denomination 100 also.
- Star series notes have the same serial number as defected notes but different prefix. The prefix of star series notes are unique.
- To facilitate easy identification, the note packet mentions on the top about inclusion of star series notes.
- The note packet has 100 notes with some star series notes, not in serial order.
- The Star series notes are legal tender.
- Since these notes are rare, they are auctioned by people.
- A list of such notes is maintained by RBI.
