C# How to compare List to itself after been changed? Equals doesn't work

I have DataGrid bounded to List<Materials> through DataSource.

After editing values in dataGrid I want to get Rows, which have been modified. Where properties of Material changed.

For this I wanted to compare item from DataGrid with same item ( by ID property) from static List which is bound to my DataGrid. I thought that it would be possible to do by comparison via Equals, but as my List<Materials> is a reference type and it's bounded to DataGrid all values in my primary list changing too.

I tried to change DataSource to copy of this list, or to array but in any case data in my source is modified.

  List<Materials> matList = Materials.allofmaterials;

  dataGridView1.DataSource = matList;


//Materials[] array = new Materials[matList.Count];
//matList.CopyTo(array);
//dataGridView1.DataSource = array;


//List<Materials> newMateials = matList;
//dataGridView1.DataSource = newMateials;

object ok = item.DataBoundItem;
Materials m1 = ok as Materials;
Materials m2 = Materials.allofmaterials.Where(x => x.ID == m1.ID).First();

if( m1.Equals(m2)) // THIS DOESN'T WORK for me
{
    //do my actions
}

How to detect what rows have been modified, and what properties exactly has changed?

I thought about dataGridView1.CellValueChanged but I'm not sure about it. Because what if user changed value once, and that changed it again to primary value. For the event it will looks like value changed, but generally value will stay the same.

I don't know the full context and can't give a definitive answer but some different approaches that focus on the collection are:

• Make a 'deep' copy of the list for comparison. List<T>.CopyTo creates a 'shallow' copy. For a deep copy, create new instances with new.
• Change Materials to be a value type, i.e. a struct or record struct. With a value type you won't have the deep copy versus shallow copy issue.
• Implement a 'dirty' state for Materials. When a property is changed, set an IsDirty property to true. Detecting the changed objects becomes .Where(x => x.IsDirty).
• If Materials is expected to be just a plain old data object with no 'smarts', a wrapper or adapter that contains a Materials instance and tracks the dirty state may be needed.

All of these approaches have trade-offs.