BillionGraves latest blog post – Irish Gravestone Symbols: https://blog.billiongraves.com/2019/03/12/irish-gravestone-symbols/.
I didn’t copy/paste most of the above link below, other than parts that had links. Each of the symbols mentioned below have headstone images for each symbol.
Irish Gravestone Symbol #1: Anchor
Some anchors on gravestones were symbolic, such as anchor-crosses that were used as a secret symbol by early Christians. But this anchor simply represents the occupation of a deceased Irish seaman.
Irish Gravestone Symbol #2: Angels
For centuries, neither angels nor human figures were allowed in cemeteries because of the commandment given to Moses as recorded in the Bible in the Book of Exodus 20:4: “Thou shalt not make unto thee any graven image.”
Irish Gravestone Symbol #3: Band and Drum Guard Emblem
Irish Gravestone Symbol #4: Calvary Steps and Ionic Cross
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Similarly, there is a type of cross called the Calvary Cross that is mounted on top of a three-tiered platform.
Beneath the pinnacle of the steps on this gravestone is an Ionic Cross which flares outward at the ends of each arm.
Irish Gravestone Symbol #5: Celtic Cross, Lily, and Shield
The Celtic Cross is a nod to ancient pagan sun-worshipers as well as a Christian symbol. This gravestone combines the Latin Cross in the forefront with a circle, representing the sun, at the back. Irish legends claim that St. Patrick introduced the Celtic cross in Ireland as a way to guide pagans to Christ.
At the center of this Celtic Cross is a lily. Lilies have long been a symbol of hope and rebirth. Even today, white lilies are the plants most often sold during the Easter season. The lily on this gravestone symbolizes the hope of a rebirth, or restoration of innocence, for the deceased.
Irish Gravestone Symbol #6: Church of Ireland Emblem
Irish Gravestone Symbol #7: Seal of the Connaught Rangers
Irish Gravestone Symbol #8: Crucifixion Etching with Mary Kneeling at the Cross
Gravestones with any form of crucifix indicate that the deceased was Catholic.
Irish Gravestone Symbol #9: IHS
Irish Gravestone Symbol #10: IHS, Shield and Ivy
Irish Gravestone Symbol #11: Ionic-Greek Cross
Irish Gravestone Symbol #12: Crest of the Irish Order of the Carmelites
Irish Gravestone Symbol #13: Jesus as a Child
Irish Gravestone Symbol #14: Last Supper
Irish Gravestone Symbol #15: Mary and Jesus
Irish Gravestone Symbol #16: Sacred Heart
Irish Gravestone Symbol #17: Shield
Irish Gravestone Symbol #18: Shield, Agony Cross, and R.I.P.
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Second, there are two small agony crosses on the base. The Agony Cross comes to a sharp point at the tip of each arm. The points represent the nails that pierced Christ’s hands and feet on the cross.
Irish Gravestone Symbol #19: Shovel or Spade
Irish Gravestone Symbol #20: IHS, Laurel Wreath, Lanterns and Winged Heads