Heart shaped (from 2015 to 2019)
[1964-2014]"NOTICE: this list is no longer updated, as this type of stamp is no longer considered to be unusual due to the number issued."
26-01-2015: Francia / France   (adesivi/self-adhesive)
30-01-2015: Slovenia
04-02-2015: Croazia / Croatia
06-02-2015: Polonia / Poland
14-02-2015: Estonia
21-08-2015: Giappone / Japan (official)
21-08-2015: Giappone / Japan (provincial)
11-09-2015: Giappone / Japan
23-10-2015: Giappone / Japan
2015: Giappone / Japan
05-01-2016: Polonia / Poland
16-01-2016: Francia / France  
(adesivi/self-adhesive)
29-01-2016: Slovenia
22-04-2016: Giappone / Japan
13-05-2016: Giappone / Japan  
29-09-2016: Bosnia HP Mostar
20-10-2016: Taiwan
11-11-2016: Giappone / Japan
23-01-2017: Francia / France   (adesivi/self-adhesive)
27-01-2017: Slovenia
03-02-2017: Croazia / Croatia
03-02-2017: Giappone / Japan
27-03-2017: Paesi Bassi / Netherlands
17-06-2017: Polonia / Poland
08-09-2017: Slovacchia / Slovakia
15-01-2018: Francia / France   (adesivi/self-adhesive)  
26-01-2018: Slovenia
14-02-2018: Alderney
31-08-2018: Malaysia
21-10-2018: Oman
21-01-2019: Francia / France (adesivi/self-adhesive)
25-01-2019: Slovenia
07-06-2019: Aland
"NOTICE: this list is no longer updated, as this type of stamp is no longer considered to be unusual due to the number issued."